28 AN INTRODUCTION TO SCIENCE 



For, it being no more a contradiction that thinking should 

 exist separate and independent from solidity than it is a 

 contradiction that solidity should exist separate and inde- 

 pendent from thinking, they being both but simple ideas, 

 independent one from another ; and having as clear and 

 distinct ideas in us of thinking as of solidity, I know not 

 why we may not as well allow a thinking thing without 

 solidity, i. e., immaterial, to exist, as a solid thing with- 

 out thinking, i. e., matter, to exist ; especially since it is 

 no harder to conceive how thinking should exist without 

 matter than how matter should think. For whensoever \ve 

 would proceed beyond these simple ideas we have from 

 sensation and reflection, and dive farther into the nature 

 of things, we fall presently into darkness and obscurity, 

 perplexedness and difficulties ; and can discover nothing 

 farther but our own blindness and ignorance. But which- 

 ever of these complex ideas be clearest, that of body or 

 immaterial spirit, this is evident, that the simple ideas that 

 make them up are no other than what we have received 

 from sensation or reflection ; and so is it of all our other 

 ideas of substances, even of God Himself."* 



It is only when entirely freed from trancendentalism that 

 philosophy has any part to play in the advance of science, 

 and probably it would conduce to clearness of thought if 

 the term were to disappear altogether from the scientific 

 vocabulary. Nevertheless the adjectives "scientific" and 

 "philosophical " usefully distinguish two aspects of thought ; 

 aspects which contrast in degree, although not in kind. By 

 scientific is meant the slow advance from observation to 

 observation, the stability of each fact being tested and 

 retested before thought trusts it to support the simplest 

 theory ; by philosophical is meant the leap beyond the 

 reach of ascertained fact and the subsequent search for facts 

 in justification of speculation. Philosophical speculation 



*Locke, " Essay concerning Human Understanding," Book II., Chap, 

 xxiii , Sect. 32. 



