Pherecydes, the Syrian, a philosopher who lived about the same time as Thales, is said by Galen to have written upon diet.
Epimenedes was a sort of Greek Rip Van Winkle, who purified Athens in the time of a plague by means of mysterious rites and sacrifices. He excelled as a fasting man, so that he was said to have been exempt from the ordinary necessities of nature, and could send out his soul from his body and recall it like the Mahatmas. He was of the class of priestly bards, a seer and prophet who was well acquainted with the virtues of plants for medicinal purposes, and as he was believed to have gone to sleep in a cave for fifty-seven years, he was credited with the possession of supernatural medicinal powers.[348]
Anaximander, born B.C. 610, is said to have been a pupil of Thales. He taught that a single determinate substance having a middle nature between water and air was the infinite, everlasting, and divine, though not intelligent material from which all things had their origin. This he called the ἄπειρον, the chaos. All substances were derived thence by the conflict of heat and cold and the electric affinities of the particles. The atomic theory is foreshadowed here.
Anaximenes was the friend of Thales and Anaximander, and all three were born at Miletus. He considered that air was the first cause of all things, or primary condition of matter; all finite things were formed from the infinite air by compression or rarefaction produced by eternal motion. Heat and cold are produced by the varying density of the primal element. He held the eternity of matter like his brother philosophers, and believed that the soul itself is merely a form of air. He held no Divine Author of the Universe, motion being a necessary law of the universe, and with motion and air he required nothing else for the constitution of all things.
Heracleitus of Ephesus, born about 556 B.C., embodied his system of philosophy in his work On Nature. He held that the ground of all phenomena is a physical principle, a living unity, pervading everything, inherent in all things—fire, that is, as he explains, a clear light fluid “self-kindled and self-extinguished.” The world was not created by God, but evolved from the rational intelligence which guides the universe—fire. Fire longs to manifest itself in various forms; from its pure state in heaven it descends, assumes the form of earth, passing in its progress through that of water. Man’s soul is a spark of the divine fire.
Anaxagoras, born about 499 B.C., was the friend of Pericles and Euripides at Athens. Seeking to explain the world and man by a higher cause than the physical ones of his predecessors, he postulated nous—that is, mind, thought, or intelligence. As nothing can come out of nothing, he did not attribute to this nous the creation of the world, but only its order and arrangement. Matter is eternal, but existed as chaos till nous evolved order from the confusion. Baas[349] says his physiological and pathological views may be thus described: “The animal body, by means of a kind of affinity, appropriates to itself from the nutritive supply the portions similar to itself. Males originate in the right, females in the left side of the uterus. Diseases are occasioned by the bile which penetrates into the blood-vessels, the lungs, and the pleura.” He undertook the dissection of animals, remarked the existence in the brain of the lateral ventricles, and was the first to declare that the bile is the cause of acute sickness.[350]
Diogenes of Apollonia, the eminent natural philosopher, lived at Athens about 460 B.C. He was a pupil of Anaximenes, and wrote a work entitled On Nature, in which he treated of physical science generally. Aristotle has preserved for us some of the few fragments which remain. The most important is the description of the origin and distribution of the veins, and is inserted in the third book of Aristotle’s History of Animals. Diogenes Laertius gives an account of the philosophical teaching of the philosopher: “He maintained that air was the primal element of all things; that there was an infinite number of worlds, and an infinite void; that air, densified and rarefied, produced the different members of the universe; that nothing was produced from nothing, or was reduced to nothing; that the earth was round, supported in the middle, and had received its shape from the whirling round of the warm vapours, and its concretion and hardening from cold.”[351]
Diogenes recognised no distinction between mind and matter, yet he considered air possessed intellectual energy.
We find in this philosopher many indications that the vascular system was in some degree beginning to be understood.[352] Mr. Lewes and Mr. Grote agree that Diogenes deserves a higher place in the evolution of philosophy than either Hegel or Schwegler.
Empedocles of Agrigentum, born about 490 B.C., now bears forward the flaming torch of medical science, and in his hands it burns more brightly still. Aristotle mentions him among the Ionian physiologists, and ranks him with the atomistic philosophers and Anaxagoras. These all sought to discover the basis of all changes and to explain them. According to Empedocles: “There are four ultimate kinds of things, four primal divinities, of which are made all structures in the world—fire, air, water, and earth. These four elements are eternally brought into union, and eternally parted from each other, by two divine beings or powers, love and hatred—an attractive and a repulsive force which the ordinary eye can see working amongst men, but which really pervade the whole world. According to the different proportions in which these four indestructible and unchangeable matters are combined with each other is the difference of the organic structure produced; e.g., flesh and blood are made of equal parts of all four elements, whereas bones are one-half fire, one-fourth earth, and one-fourth water. It is in the aggregation and segregation of elements thus arising that Empedocles, like the atomists, finds the real process which corresponds to what is popularly termed growth, increase, or decrease. Nothing new comes or can come into being; the only change that can occur is a change in the juxtaposition of element with element.”[353]