ON THE STUDY OF PHYSICS 309 



was practiced by every healthy mind before ever such 

 rules were written. In the study of Physics, induction 

 and deduction are perpetually wedded to each other. The 

 man observes, strips facts of their peculiarities of form, 

 and tries to unite them by their essences: having effected 

 this, he at once deduces, and thus checks his induction. 

 Here the grand difference between the methods at present 

 followed, and those of the ancients, becomes manifest. 

 They were one-sided in these matters: they omitted the 

 process of induction, and substituted conjecture for ob- 

 servation. They could never, therefore, fulfil the mission 

 of Man to "replenish the earth, and subdue it." The 

 subjugation of Nature is only to be accomplished by the 

 penetration of her secrets and the patient mastery of her 

 laws. This not only enables us to protect ourselves from 

 the hostile action of natural forces, but makes them our 

 slaves. By the study of Physics we have indeed opened 

 to us treasuries of power of which antiquity never 

 dreamed. But while we lord it over Matter, we have 

 thereby become better acquainted with the laws of Mind; 

 for to the mental philosopher the study of Physics fur- 

 nishes a screen against which the human spirit projects its 

 own image, and thus becomes capable of self-inspection. 



Thus, then, as a means of intellectual culture, the study 

 of Physics exercises and sharpens observation: it brings 

 the most exhaustive logic into play: it compares, ab- 

 stracts, and generalizes, and provides a mental scenery 

 appropriate to these processes. The strictest precision of 

 thought is everywhere enforced, and prudence, foresight, 

 and sagacity are demanded. By its appeals to experiment, 

 it continually checks itself, and thus walks on a founda- 

 tion of facts. Hence the exercise it invokes does not end 



