CHAP. XI. 



Netston's Theory of Colours^ indicated by Pythagcrat 

 and Plato. 



1. 1 HAT wonderful theory, whereby is invest!* 

 gated and distinguished from one another, all that va- 

 rifly of colours which enters into the composition of 

 that uniform appearance, light, might of itself suffice 

 to establish for ever the glory of Sir Isaac Newton, 

 and bean eternal monument of the extraordinary sa- 

 gacity of that great man. That discovery seems, by 

 its importance, to have been reserved for an age when 

 philosophy had arrived at its fullest maturity ; and 

 yet it is to be found among some of the eminent men 

 of the first antiquity, whose genius had no occasion 

 for the experience of many ages to form it, as is 

 strikingly evident from their having given birth to the 

 sciences. Of this number are Pythagoras and Plato. 

 The former of whom, and his disciples after him, en 

 tertained sufficiently just conceptions of the formation 

 of colours. They taught, * that they resulted solely 

 from the different modifications of reflected light ; J or 

 as a modern author, in explaining the sentiments of the 

 Pythagorean*; expresses it, 4 light reflecting itself with 

 more or less vivacity, forms by that means our di fie rent 

 sensations of colour J Those same philosophers of the 

 Pythagoric school, * in assigning the reason of the 

 difference of colours, ascribe it to a mixture of the 

 elements of light ; and divesting the atoms, or small 

 particles of light, of all manner of colour, impute 

 every sensation of that kind to the motions excited in 



