Astronomy was looked upon as an exceedingly practical study, because it was by this science that the festivals of the Church were dated. The astronomers of the time knew something of eclipses and they had tables of stars and planets. They studied the observations made by the wise men of the East for many centuries, and really learned a great deal. Unfortunately, they made one great mistake. For four hundred years it has been known that the earth and the other planets revolve around the sun. In the Middle Ages, however, people believed that the sun revolved about the earth. The sky, they thought, was a vast hollow sphere which revolved once a day. It was because of this mistake that when they tried to reason about what they had seen, their conclusions were all wrong, no matter how correct their observations might have been.

Now when people believed that the whole starry universe was made for their especial benefit, it was not very unreasonable to take it for granted that the stars, their arrangement in the sky, and their movements had something to do with human affairs. Anything unusual was always alarming. Comets were a source of terror. No one knew whence they came or whither they were going. They were uncanny, and even the educated feared some awful disaster when one of these fiery wanderers appeared in the sky. In the middle of the fifteenth century, a large comet was seen which terrified all Europe. Even before its appearance people were in dread, for the Turks had crossed the Hellespont, and there was reason to believe that they would overrun the Continent. Then came the added horror of the comet, and no one could tell what awful calamity this might portend. It is no wonder that the Pope ordered the church bells to be rung at noon, and the Ave Maria to be said three times a day instead of twice. To this prayer was added the petition, "Lord, save us from the Devil, the Turk, and the Comet."

Comets, fortunately, did not appear very often, but it was believed that the other heavenly bodies, also, had an effect upon people and could make them successful or unsuccessful. A man who could interpret the significance of the heavens was called an astrologer, and the science, or make-believe science, was called astrology. When a child was born, the father hurried away to an astrologer, if he could afford to consult one, to have what was called a horoscope calculated, that is, to have its future life predicted according to the aspect of the heavens at its birth. The most important constellations are situated in a wide belt around the heavens called the zodiac, and are therefore called the signs of the zodiac. There are twelve of these constellations: Aries, or the ram; Gemini, or the twins; Leo, the lion; Capricornus, or the goat; and others. The one which was in the ascendant, or just risen above the eastern horizon, at the time of the child's birth, was supposed to have great influence upon his life. But this was only the beginning of the astrologer's calculations. He fixed a point in the sky according to the position of the sun and moon at the time, and, beginning at that, he divided the heavens into twelve "houses." These houses were divided and subdivided. To each house some planet was assigned, and every planet had its special influence. Jupiter, for instance, had power to give one riches and honors, Venus would bestow love and warm friendship. If, then, Jupiter chanced to be in the house assigned to him and in a favorable sign, his influence upon the child would be so strong that he could hardly help winning wealth and distinction. People consulted astrologers about the proper time to begin a journey or a business undertaking, about a favorable day for a marriage or the coronation of a king, and, indeed, so far as they could afford it, about an endless number of even the smallest affairs of life.

Even in medicine the position of the planets was of the utmost importance. When a doctor was sent for, he came on horseback with the bells on his bridle rein jingling so merrily that he could be heard a long way off. An assistant followed him and as many servants as his purse would permit, bearing five or six instruments and numerous sorts of ointment. When he reached the home of the sick man, his first business was not to count his pulse or note his temperature, but to inquire under what constellation he was born. With this knowledge he would set to work to ascertain what remedy would be of service. But, however valuable the medicine might be and however much it might be needed, it must not be taken when the moon was in an unfavorable sign; for then it would do harm rather than good. When an epidemic appeared, it was of course laid to the stars, or the power of evil spirits. Two unfavorable planets meeting in the same degree of the zodiac would account for any pestilence, or so people thought. There was, however, one other way of explaining the appearance of any general illness, and that was to lay it to the Jews. In France, Germany, and Italy, Jews were many times accused of poisoning the wells or even the air, and were either imprisoned or put to death on this charge.

Some of the medicines of the time were most absurd, and many were revolting. Gold filings were thought good for leprosy, and so was an adder boiled with leeks. A more agreeable remedy for the illness of a child was to weigh the child and then offer up at some shrine its weight in bread or grain or cheese or wax. Many herbs were used, such as sage, wormwood, and pennyroyal. Medicines were hardly expected to do much good of themselves. To make a dose powerful, the sick man must repeat a certain Psalm twelve times together with several Paternosters while the medicine was being prepared. It was far more likely to effect a cure if he could take it at the shrine of some saint. With some remedies one should always repeat a charm.

Physicians are described as wearing expensive robes of silk with trimmings of fur. "Physic" in Piers Plowman  wears a hood richly trimmed with fur, and gold buttons on his cloak. They demanded large fees and received them. In other cases a man might choose whether to purchase or to do without; but in illness there was left him only the highwayman's choice, "Your money or your life." Chaucer makes a fling at these exorbitant charges and says of the learned doctor among his Canterbury pilgrims,

Poor folk had not the money necessary to buy their lives of these great doctors, and therefore they went with their ailments to the barber. He was permitted by law to apply plasters and ointments to wounds that did not threaten to become dangerous, and often to give simple remedies. In most diseases, the first treatment was to bleed the patient, and the barber's pole of to-day is a reminder of the custom. In France, before any serious operation could be performed, the bishop or the feudal lord of the patient had to be consulted. were made use of for remedies or to keep away illness. These consisted of a stone or a piece of metal upon which was cut a figure or an inscription. In the earlier part of the Middle Ages, runes were often used for the inscriptions. These were only the letters of the earliest northern alphabet; but so few people could read that they were looked upon as something having magical powers. In later times, most talismans were brought from the East, and were engraved with inscriptions in Persian or Arabic. Even in health these tokens were highly valued. A species of charm known as a philter was supposed to have the power to arouse love. Sometimes a magic drink for the same purpose was prepared and given to the person in question; but oftener the one who wished to become beloved wore a philter consisting of powdered loadstone, nail-parings, and human blood, or other absurd combinations. If a man wished to win honor, he might cut the image of Jupiter on a white stone or a piece of tin; and if this was done when the planets were favorable, he would be sure to gain his wish. Of course there were stories upon stories of cures wrought in illness by such means. Roger Bacon, who was perhaps the most sensible scientific man of his age, declared that charms and talismans were of much value; but he explained that this was not because they acted as remedies, but because they made the patient calm and hopeful and thus aided in his recovery.

It is a wonder, however, that when people were sick, they should ever have expected charms or anything else to be of service, for so many illnesses were thought to be caused by witchcraft. Some persons were believed to possess what was known as the "evil eye." Whoever first met their gaze in the morning was sure to pine away and die; and, indeed, some evil was likely to befall one upon whom they looked at any hour of the day. If a man wished to take the life of an enemy, he could do so conveniently by driving a nail or a wooden peg into a wall, pronouncing the name of the victim at each blow. Another way was to shoot an arrow into the air, praying to some demon to direct its flight to the person named. This arrow would leave a wound which was invisible, to be sure, but which would certainly cause death within three days. Another method of ridding one's self of a foe was to make an image of him in wax. Under the right arm of the image one must place the heart of a swallow, and under the left arm its liver. Whatever injury was done to the figure was supposed to be felt by the person whom it represented. If a needle was pushed into its side, the person was expected to feel a sharp pain in the side. In case of sudden death, people thought first of witchcraft, and it was sometimes dangerous to the safety of even an innocent man if his enemy died too unexpectedly. It was far safer to build fire of wood and vervain, set the waxen image before it, and let it melt. Then the person would slowly but surely waste away. This belief in the waxen image was so firmly fixed that if a man had a hawk which he could not succeed in managing, he would sometimes send a waxen image of it to the shrine of some saint that he might have better success.

Besides the danger of being bewitched, there were the four "humors," or qualities, to be reckoned with. All things are made of earth, air, fire, and water, but in varying proportions, declared the wisdom of the Middle Ages. Earth has the humor of being cold and dry; water of being cold and moist; air of being hot and moist; and fire of being hot and dry. It went on further to say that earth corresponded to autumn and the melancholic temperament; water to winter and the phlegmatic; air to spring and the sanguine; and fire to summer and the choleric. If these humors were perfectly balanced, the person was well—and to this day we keep the phrase "good-humored"—but if there chanced to be too much of any one of them, illness was the result; and it was the business of the doctor to decide which humor was in excess.

Mixtures to cure diseases were often prepared by the alchemists, or chemists of the time. With the chanting of charms and the drawing of magic circles an alchemist would prepare a draught warranted to heal a sick man, give pleasant dreams, or make one invulnerable. To the common folk, their work was so mysterious and the sights and sounds from their laboratories so strange and awe-inspiring that whenever they passed the house of an alchemist, they crossed themselves and prayed to be delivered from the power of the Devil. They were ready to believe the most absurd stories of the abilities of these men. One was said to be able to call back to his purse whatever coins he might have paid out of it. Another was believed to have made a wooden image that would rise from its seat and open the door whenever a knock was heard. Most mysterious and most popular of all such wonders was the brazen head which Roger Bacon was said to have made. Success in his undertakings and a vast amount of knowledge were to come to him if he only heard it speak. When he had become too weary to listen any longer, he set an assistant to watch it. While the master slept, the head suddenly spoke. "Time is," it said. "There is no use in arousing my master to hear what every one knows," thought the assistant; and he let Bacon sleep on. The head spoke again, and said, "Time was." This, too, the assistant thought was of no importance. Half an hour later it spoke for the third time. It said, "Time is past," fell from its place, and was broken to fragments; and so it was that Bacon himself, its maker, never heard it speak.

The alchemists experimented on various substances, treated them by fire, then by water, then united them, and carefully noted the results. Thus far they were in the true path of science; but they could make little advance beyond this, because they began their work with some false notions which they could never lay aside. They believed, for instance, that earth, air, fire, and water were peopled by demons; and when the facts did not agree with their theories, they explained matters by saying that the demons were interfering. Of course they believed in the influence of the stars, and often they tried to connect the stars and the earth by odors. If a man wished to secure the influence of the sun, for instance, he mixed saffron, amber, musk, clove, incense, the brain of an eagle, and the blood of a cock, and burned them.

The alchemists had three aims in particular. One was to discover a "universal solvent," that is, some substance that would dissolve everything into its elements. The second was to make an elixir that would enable a person to keep youth and life as long as he chose. Even the reasonable Roger Bacon thought this was quite possible; and after the discovery of America, people felt sure that somewhere in the wonderful new land the elixir would be found. Many believed that the marvelous draught would not be compounded by an alchemist, but was only the water of some magic fountain. When Ponce de Leon made his voyage to America in 1512, he set out in eager hope of finding this fountain of youth, for he was fast becoming an old man, and he longed to be young again.

The third quest of the alchemists was to discover what was known as the "philosopher's stone." They thought that all metals were made of sulphur and mercury, that in gold the sulphur and mercury were pure, while in the baser metals they were more or less corrupt. If the "stone" could be discovered, this corruption would be cured or driven away from any metal, and pure gold would remain. Generation after generation of alchemists labored in this quest. Many of them were honest and were trying their best to make discoveries that would be of value to mankind. Others sought only a method of making gold and so winning riches for themselves. Then, too, there were numerous rascals who had a smattering of the learning of the alchemists and went about persuading people that they could turn the baser metals into gold or silver, and getting money from them for sharing the secret of the method. Chaucer tells the story of one of these quacks who turned mercury into the purest of silver before the face and eyes of a trustful priest and obtained forty pounds from him for the recipe. The secret was that he brought with him a beechen coal in which a hole had been bored and filled with silver filings. It was easy to slip this coal in with the others in such a way that the wax which stopped up the hole would melt and let the silver fall into the crucible. The second trick of the deceiver was to stir the mercury in the crucible with a hollow rod in which was an ounce of silver filings kept in with wax in the same manner. After the priest had paid his forty pounds and the quack had disappeared, he tried his magical recipe; but in spite of all his efforts not a bit of silver could be found in the crucible.

The alchemists did not discover the philosopher's stone, but in their experiments they did gain some useful knowledge. Among other things they discovered soap, they learned how to separate silver from lead, and how to make porcelain. The Chinese knew of gunpowder many centuries earlier; but Roger Bacon is thought to have learned that with sulphur, saltpetre, and charcoal an explosion might be produced, and so to have discovered it anew. The ideas of some of the alchemists ran far out into the future. Bacon predicted that the time would come when boats would move without oars, and wagons without animals to draw them, when men would be able to fly through the air, and bridges without any supporting piers would span the widest rivers. He believed, too, that an elixir would be discovered that would enable people to live as long as they chose.

Several of Bacon's predictions have long ago come to pass; but they probably seemed to the good folk of his time far more absurd than many strange things that appeared to them a matter of course. All through the period people of education believed that the earth was a sphere; but they were ready to accept without question the wildest stories of what might be seen in the parts that were unknown to them. In Africa, it was said, great dragons were found from whose brains precious stones might be taken, and also beasts so venomous that whoever looked them in the face fell dead. It was believed that tribes lived in that country who had three or four eyes in their foreheads. Other tribes fed upon nothing but honeysuckles dried in smoke by the sun. Ireland was the special country of wonders. In one lake, so the story went, a rod of hazel would turn to ash and one of ash to hazel. Another lake had quite as amazing properties, for if a rod was made to stand upright in the water, the part in the earth became iron, that in the water was turned to stone, while that above the water was not changed. In Ireland, too, there was said to be a little island whose inhabitants could never die. When they were overcome with the weaknesses of age, they had to be carried elsewhere that they might find relief in death. In Finland, so people thought, certain men had the power to raise the wind. They tied knots in a cord, and if they desired a gentle breeze, they let out the cord to one knot. For a storm, they let out to four or five knots. Concerning India, people would believe the most fantastic imaginings. Its ruler was thought to be one Prester John, or priest John, who had governed the land for many centuries. Some of his subjects were said to be more than five cubits in height. Others had dogs' heads and barked like dogs. Near the source of the Ganges were men who had no mouths. Naturally, they neither ate nor drank; but they lived on the perfume of flowers.

Concerning animals and plants there was a sort of imaginative natural history which was stated in so authoritative a manner and with so many details that it must have needed a brave man to doubt its truth. "A griffin," says an old book, "is a flying thing. Its head and wings are like the eagle's; the rest of the body is like that of a lion." The "enchirius," whatever that may be, is described as a little fish half a foot long which clings to a stone when a storm is coming, that it may not be blown about. Its ability to cling must have been considerable, for it was said that if it caught a good hold of a ship, it could hold it perfectly quiet. Still more startling is the statement that when a whale becomes old, earth collects upon his body to such an extent that herbs and small bushes take root and grow. Cranes, it was said, seat themselves comfortably on the ground when they are weary; but they always leave watchers on guard. The watchers stand on one foot. In the other foot they hold a little stone, so that if they chance to go to sleep the stone will fall and arouse them. No serpent will come into the shade of an ash tree; and if the creature be encircled partly with ash leaves and partly with fire, he will flee through the fire rather than touch the leaves. The young ravens live on dew until they begin to show black feathers. Then the mother bird feeds them. Toads and serpents cannot bear the fragrance of the grapevine blossom, and when the vine is in bloom, they escape from the vineyard. These are some of the "facts" of natural history as believed in the Middle Ages. Folk were taught that there were satyrs with horns and the feet of goats, cyclops with one eye in the middle of their foreheads, and people with eyes in their shoulders and neither nose nor head. They believed that certain men had made pacts with Satan, and in consequence were obliged once a year to take the face of a dog, a wolf, a bull, or a pig, and that these monsters searched the woods to find children to devour. But of all the fancies that were once regarded as facts of natural history, that of the phœnix was dearest to the good people of the age. There was only one phœnix in the world at a time. It lived from three to five hundred years, then, when it began to be weary and feeble, it made a nest of sweet smelling woods. This was set afire by the rays of the sun; and when it was well ablaze the bird entered the flames and was burned to ashes. Three days later, a little worm was found in the ashes, which grew and put on feathers and became another phœnix to take the place of the first. Cassia, it was said, was found in the nest of the phœnix, and either fell to the ground of its own accord or was struck down by leaden arrows. For some reason, people were not so willing to accept this story of the cassia as other marvels, and some ventured to say boldly that the tale was invented to raise the price of the article. About the mandrake, however, they were ready to believe anything, no matter how impossible. The root of the mandrake is often forked, and has a rough resemblance to a human body. That was enough to serve as a foundation for a story that it was the offspring of some person who had been put to death for murder. It shrieked when it was pulled, said the story; and to pull it was at best a dangerous business. He who set about it must wait until the wind blew from a favorable quarter. He must make three circles about the plant with a sword; but he must not venture to dig until after the sun had gone down. If one obeyed these directions carefully, he might hope to escape harm.

Various methods of divination were resorted to in order to read the future or to learn whether an enterprise would be likely to succeed. One way was to hang a ring inside a pitcher by a thread and read the fates by the number of times that it struck the sides of the pitcher. Sometimes a fire was built of certain kinds of wood, and it was believed that the shape and movement of the flames and the smoke would reveal things that were about to be. One might fast and pray and then open a Bible. The verse upon which his eye first lighted would be significant. Sometimes instead of the Bible a copy of Virgil was taken. To discover hidden treasure, one must use the hand of a man who had been hanged. Whether the predictions of a sorcerer were eventually shown to be true or false, the people believed in sorcery just the same; for if his words proved false, they simply declared that he was not a true sorcerer, and that some man of greater powers would have succeeded. Indeed, so far as the sorcerer himself was concerned, it was not well to succeed too often; for all magic was supposed to be more or less connected with the Devil, and if the magician was too successful, whispers would go abroad among his enemies that so intimate a friend of Satan ought to be burned to death or at least to be imprisoned. It was believed that at stated times sorcerers and witches met together in some gloomy and unlawful place to boast of the tricks they had played and learn of one another and of Satan how they might still further deceive those who consulted them. This meeting was known as the "Witches' Sabbath."

One great obstacle in the way of real progress in science was the general belief in analogy. A magnet will draw steel; therefore it was concluded that it would draw pain from the body. The "universal solvent" which the philosophers were ever hoping to discover would separate every substance into its elements; therefore it was supposed that it would also dissolve disease and do away with it. Another difficulty was that the causes of the phenomena of nature and the relation of cause to effect were so little understood that with most people if one event happened after another, this was regarded as sufficient proof that it was caused by that other. No matter how absurd and useless a medicine might be, if a sick man recovered after taking a dose of it, no one questioned that the medicine had wrought the cure.

A third great weakness in the science of the times was that instead of studying nature and trying to explain what they saw, the philosophers set out with definite opinions on numerous points and tried to make nature and their own observations fit the theories. The alchemists, as has been said, set out with the belief that all metals were made of sulphur and mercury, and they could never understand why the metals would not act like sulphur and mercury. Another difficulty was that if any two things looked alike, the philosophers were certain that there was some relation between them; but to discover what it was they used their imagination rather than their observation. For instance, crystal looks like ice; therefore they decided that if ice could be kept for many years, it would turn into crystal. Pearls have a dewy appearance and are found in the shells of oysters. That was proof enough that pearls came from dew; and the philosophers decided that in the nights of early spring the oyster opened its shell to receive the drop of dew and changed it into a pearl. In a thunderstorm, the sky is often covered with heavy, swiftly changing clouds; therefore it was regarded as evident that thunder is the noise produced by breaking up the clouds. This same fashion of fancying a connection between any two things that resembled each other was also carried into medicine. The wood sorrel has a heart-shaped leaf; therefore it would cure any disease of the heart. Liverwort, or hepatica, has a three-lobed leaf, and the liver has three lobes; therefore hepatica was of course beneficial to the liver. Certain ferns have seeds so tiny that they can hardly be seen by the naked eye; therefore fern seed had the power of making one invisible.

Such were some of the beliefs and superstitions of the people of the Middle Ages; but the folly of these vain imaginings was realized by some. One man who wrote an encyclopædia of general knowledge exclaimed against trying to read the future by noting the flight of a flock of crows, and said that he did not think it lawful to believe that God had revealed his counsel to crows. It is no longer necessary, as was the case in the seventh century, for a worthy bishop to beg his clergy not to observe Thursday, the day of Thor or Jupiter, as a day of rest, not to fear that a sneeze proved the presence of evil spirits, and not to visit sorcerers or makers of talismans. Nevertheless, there are many good folk even now who trust to absurd treatments of disease, who believe in signs and omens, in lucky and unlucky days and numbers, in the misfortune portended by the breaking of a or by the howling of a dog under the window, and in a thousand other superstitions; and even to-day the plain common sense of the man who did not believe that God revealed his counsel to crows would often be most welcome.