Page:Greek Biology and Medicine.djvu/119

 PROGRESS IN ANATOMY fevers, or whenever it falls below, as at the approach of death. From Homer downward, the breath of man suggested itself as the vital principle or its vehicle. How about its re- lation to the body's heat? This perplexing question brought great confusion.®* Air seems both hot and cold; and any one can blow hot or cold with the same mouth. Was the vital and necessary breathing of the air, in and out, a cooling or a warming of the body? Opinions wavered and contradicted each other for centuries. Apparently — the whole matter is exceedingly obscure — the early physicists with Hippocrates were ranged on the side of warming, and Aristotle with his great influence on the cooling side. Nearly two thousand years later, Harvey remained perplexed. After his death, the search was carried on more vigorously for some needed and explanatory process analogous to the burning of combust- ible things, in fine, for a process of combustion. The goal was reached through the discovery of oxygen and the slow-won knowledge of its functions in the human economy. [97]