nonent:

a thing that has no existence

 

Anaximander:

 (610-546 BC) pre-Socratic Greek philosopher, lived in Miletus (Ionia); belonged to the Milesian school and learned from Thales, becoming the second master of that school; Pythagoras was a pupil.  This school introduced new opinions (contrary to the prevailing believes in anthropomorphized gods) where nature was methodologically observed to find explanations for natural phenomena; considered one of the first truly scientific philosophies.

 

stereometry:

the measurement of volumes

 

Helmholtz:

(1821-1894) German physician & physicist, made significant contributions to physiology and psychology (optics, mathematics of the eye, theories of vision, nerves), physics (electromagnetism) philosophy (philosophy of science)