THE DEVELOPMENT OF PSYCHOLOGY. 293 



tion of the "original, certainty, and extent of human knowledge." 

 Berkeley avowed that his motive, in investigating the nature of per- 

 ception, was to provide a bulwark against the atheists. Hume is es- 

 sentially theological, and in his " Inquiry concerning the Human Un- 

 derstanding," a section on Miracles stands side by side with one on 

 the Idea of Necessary Connection. Reid wrote his "Essays on the 

 Powers of the Human Mind " to refute Hume, and became, with this 

 theological motive, the founder of Scotch psychology. Kant under- 

 took his " Criticism of Pure Heason," and thus established a priori psy- 

 chology, to show against Hume that the ideas of God, freedom, and 

 immortality, could not be disproved by mere empirical reasoning. 

 And the impulse which Hamilton, through Mansel, communicated to 

 Psychology, by the new face he gave to the old problem of the Infinite, 

 was a theological movement in its origin. 



Under whatever name we give to it, under whatever form it may 

 hereafter assume. Theology, the science of causes, essences, and origins, 

 will play, as it has hitherto played, an important part in the develop- 

 ment of the mental sciences, and especially of Psychology. When 

 physical science is driving its ploughshare into untrodden regions 

 till now only gazed down upon by the metaphysician in his balloon ; 

 when the speed of thought itself is measured ; when the most complex 

 effort of quantitative reasoning is proved to be fundamentally indenti- 

 cal with the simplest perception of relation ; when the nature of intel- 

 ligence is tracked upward in graduated sequence from the Padiata 

 and Articulata to Newton and Shakespeare ; and when the physical 

 sides of all but the most subtle mental phenomena are being identified ; 

 the temptation is great to suppose that we are nearing the goal — that 

 as so many laws of mind have been explained by physical laws, and 

 so many facts interpreted in physical terms, the time is at hand, or at 

 least will come, when the nature of causation, and of the substance 

 of mind, and of the relation of phenomena to their source, and of that 

 inscrutable source itself, will yield their secrets to the analysis of the 

 inquirer armed with the weapons of physical science. Whatever power 

 stands in the old place of Theology, which is dead — whether Meta- 

 physics, if that be not dead also, or some " Unknowable " section of 

 our compendiums of first principles — will show all such Comtist dreams 

 to be vain, by eternally asking the unanswerable questions which it 

 lias been asking since the beginning of speculation. And each old 

 question newly asked after each fresh advance of physical science 

 tends to restore the equilibrium deranged by the operation of that 

 dynamical factor, the history of the effects of which we will now 

 briefly sketch. 



The application of physical methods to the phenomena of mind 

 we believe to have originated in the fact that, outside the territory 

 which (as we saw by the quotation from St. Thomas) was sacred to 



