Chapter 2 



The Smallest Particles of Matter 



Until comparatively recently, atoms were thought to be the 

 smallest units of matter. In fact, the word atom, derived from 

 the Greek, literally means "that which cannot be cut." About 380 

 B.C. Greek philosopher Democritus, allowing his imagination to 

 outrun his senses and all means of observation then known, main- 

 tained that infinite space is populated by an infinite number of 

 atoms which he conceived to be eternal, homogeneous, invisible, 

 and indivisible. The smooth, round atoms of water were supposed 

 to roll readily past each other, whereas the jagged atoms of iron 

 hooked tightly together. Democritus regarded the soul as consist- 

 ing of round, smooth and exceptionally mobile atoms which in the 

 head, control reason; in the heart, anger; in the liver, desire. Life, 

 he thought, requires the inhalation of fresh atoms to replace those 

 lost by exhalation; so that when respiration ceases, death results, 

 and the soul perishes with the body. 



To explain nature, Plato and Aristotle invoked human reason 

 and reactions, rather than matter and experiment. Aristotle con- 

 sidered that four primary qualities — hotness and coldness, wetness 

 and dryness — combined in pairs to form the four "elements," 

 earth, air, fire and water. These "elements," described essentially 

 by human reactions, united in various proportions to make up 

 various kinds of matter. 



The atomic views of Democritus were temporarily revived by 

 Epicurus (341-270 B.C.) and Lucretius (95-51 ? B.C.); but during 

 the Middle Ages the ideas of Aristotle prevailed, even though his 

 four elements competed with a subsequent alchemistic notion that 

 salt, sulfur and mercury are the basic "principles" or "essences." 

 Thus Chaucer (1340-1400) wrote of the Clerk of Oxenford: 



For hym was levere have at his beddes heed 

 Twenty bookes clad in blak or reed 

 Of Aristotle and his philosophy, 

 Than robes riche or fithele or gay sautrie. 



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