Know Thyself 39 



wisely. 



So I think we must conclude that this supreme poet, 

 too, helped to convince man that if he would really 

 know himself, he must know himself as a physical as 

 well as a spiritual being. The ancient injunction must 

 be adopted in the temples of Poesy and all Art no 

 less than in those of Philosophy and Religion and 

 Science. 



What, finally, is our era contributing to man's un- 

 derstanding of himself? What does what must the 

 injunction mean in the light of modern knowledge? 

 Under the necessity of being brief we will limit the 

 inquiry here to the realm of objective science, and will 

 notice six great achievements during the three hun- 

 dred years since Shakespeare and Harvey, which seem 

 to me of great importance in their bearing on the 

 question. These are (1) the formulation of the law 

 of gravitation; () the discovery of the law of con- 

 servation of energy; (3) the demonstration of the 

 absolute dependence of living beings on a few well- 

 known non-living chemical substances and physical 

 conditions, and the discovery of many of the laws of 

 this dependence; (4) the demonstration that both indi- 

 vidual living beings and kinds or species of such be* 

 ings, originate from other individuals and species, and 

 so far as can be made out, that they originate in no 

 other way; (5) the demonstration of the enormously 

 wide, if not the universal prevalence in the living world 

 of individual specificity, so deep-seated as to implicate 



