t 4 ] 



into water. This affords a visual sensation of a kind 

 which they could compare with that afforded by a 

 bent stick as seen through air alone. By means of 

 this inappropriate syntaxis the philosophers arrived at 

 the conclusion that they saw the straight stick bent 

 in the water, and, instead of seeking for a more suit- 

 able syntax, such as that which is suggested to our 

 minds by the idea of refraction, they accused the 

 senses of deception. Yet they knew that an object 

 when observed 'from a distance subtends a smaller 

 visual angle than the same object when near to the 

 observer, and they do not appear to have found any- 

 thing deceptive in this, because the appropriate syntax 

 was familiar and occurred to them immediately. 



The earliest Greek philosopher of whose system 

 we have any very definite record was Xenophanes 

 (born 620 B.C.), the founder of the Eleatic school. 

 His central doctrine was the all-embracing unity and 

 unchangeable nature of " The One ; " a doctrine 

 which is comparable to, though not identical with, 

 the theological idea of an all-pervading Deity. Rely- 

 ng upon their deductions from this doctrine, the 

 Eleatics asserted that there is no such thing as change* 

 and that all apparent changes are only deceptions of 

 the senses. Heraclitus (535-475 B.C.) on the other 

 hand held that, although the senses are deceptive, yet 

 only those who do not reason rightly will be deceived 

 by them. He asserted, not only that everything 

 changes, but that change is the sum of all existence ; 



