Aristotle’s family had been long identified with medicine. His father was court physician to the King of Macedonia and several of his ancestors had similar posts. Therefore, in a sense, it was natural for him to seek learning. For some years he was a student of the philosopher Plato at Athens. He was a more practical man than his teacher, favoring experimental observation as supplemental to philosophy.
Universal truth and knowledge were the goals Aristotle set for himself. Also he believed it well to keep in the good graces of the rulers. When Alexander the Great was 13 years old, Aristotle was appointed his teacher and from that time on had a deep influence on the pupil who, they tell us, came to tears because he had no more worlds to conquer. Aristotle later headed the Peripatetic or “walk about” school at Athens, so named because knowledge was imparted from teacher to student as they strolled about the groves. Aristotle wrote authoritatively on almost every subject. The sun, light, and vision, of course, received the attention of this philosopher whose word on philosophic and scientific matters was accepted by many without question as law for centuries. Even today many principles first enunciated by Aristotle are still generally respected in philosophy.
In Aristotle’s book titled Problems there was described the phenomenon of sunlight passing through a square hole and still casting an image of a round—not square—sun on the wall or floor.
This was an astounding discovery! It may strike the reader as strange, but he may easily convince himself by making a little experiment: cut a square hole in a piece of dark paper and let the image of the sun fall on a mirror or other smooth surface and you will see that the sun is still round despite the square hole. As a word of caution, one must be careful to avoid eye strain when viewing the sun and its reflections. Several of the principal characters in motion picture pre-history ruined their eyes by studying the sun for too long a period at one time.
Aristotle’s square hole and round sun experiment was a beginning and scientists were starting to learn something important about light and optical phenomena.
Aristotle also made a valuable contribution to the study of vision. In his book, On Dreams, he noted the existence of after-images, a persistence of vision phenomenon. That faculty contributes vitally to the motion picture effect. A common example is that a whirling firebrand appears to make a complete continuous circle of fire. A strong light or image of any kind will be visible to the eye for a moment after the physical stimulus has been removed.
Aristotle also was interested in color and in a study in this connection he noted that certain given plants were bleached by the sun. This was the initial scientific observation in the chain which ultimately, though indirectly, led to photography.
Archimedes (287–212 B.C.), a half-century after Aristotle, developed at Syracuse, then a Greek colony on the island of Sicily, the first recorded light apparatus, “The Burning Mirrors or Lenses.” Famed as the first great geometrician, Archimedes is best known for his principle upon which all ship construction is based—the buoyant force exerted by a liquid is equal to the weight of the displaced liquid. In other words, a shaped object of metal, such as a ship, will float if it displaces a sufficient quantity of water. King Hiero of Syracuse, a relative of Archimedes, gave him the problem of determining whether or not a new crown he had received was made of pure gold, as ordered, or whether the gold had been mixed with silver. This would have been no task at all if the King had not been fond of the crown and wished the information secured without damaging it in any way. As was the custom in those days, Archimedes considered the problem one afternoon at the local bath which served the double function of promoting cleanliness and of fostering every kind of discussion. It was the gentlemen’s club of the day and place.
Archimedes liked to bathe with a tub full of water and this particular afternoon he noted that a considerable amount of water was spilled over the sides of the tub as he stepped in. He immediately and correctly concluded that there was a relation between the mass of his body and the weight of the water displaced. Then according to tradition he rushed home, through the streets of Syracuse, naked, in order to test the King’s crown, shouting “Eureka—I have found it.”
This talented Greek was keenly aware of his scientific prowess and was not a man to keep his ideas secret. He promised to lift the world with a lever (the principle of which he had developed scientifically) provided someone would furnish him a fulcrum. There were no takers.