THE SCHOOL OF ATHENS: Focus on Diogenes

Many ancient Greek philosophers were named Diogenes, but this fellow is most likely Diogenes of Apollonia, who was probably active in the 430s and 420s BC.  Diogenes believed that everything is ultimately composed of air, and that air is essential for being able to think (plants allegedly cannot think because they are not hollow and cannot take in air.) He posited in humans an "anatomy of vessels" to explain features of our physiology.