2 THOUGHTS ON OUR CONCEPTION OF PHYSICAL LAW, 



are met in the investigation of any subject, when the sole aim is to find out the 

 truth of the matter, and I have thought it proper to point out some of the diffi- 

 culties to which we are subject in arriving at our conceptions of physical law. 



The study of physical science has endowed the human mind with an attribute 

 which is usually ascribed to and is thought to be characteristic of the Divine 

 Mind. I refer to the power of prophecy. The astronomer can predict the posi- 

 tion of the planets for generations to come, basing his predictions on the assump- 

 tion — an unproved assumption — that only those causes which he has considered 

 will act in the future, or, in other words, that the present order of things will con- 

 tinue. His power of prediction does not, however, extend indefinitely into the 

 future, for there are, doubtless, many minor disturbances or perturbations, too 

 small to be detected by the instruments which he can command, without many 

 centuries of observation, the effects of which will become plainly apparent after 

 the lapse of ages — that is to say, his power of prophecy is limited by his ignorance 

 of certain facts, and, possibly, by his inability to solve the equations involved in 

 a complete discussion of the subject. 



It is for precisely the same reason that we cannot foretell the future destiny of 

 every person in the world. But to a m^nd possessing all knowledge, and of infinite 

 power, the one problem would evidently be as simple as the other. 



We can readily imagine a being, possessing sufficient knowledge and ability, 

 to calculate the orbits of every person now living. Such a being must know all 

 that is to be known in regard to our mental and physical organisms, and the cir- 

 cumstances under which we are and will be placed. Having thus the initial stage 

 and being able to trace succeeding events as logical sequences of the present, 

 such a being could predict exactly what each of us tvill decide to do, under the presefit 

 and all succeeding circumstances — could predict how far we will be physically and men- 

 tally able to carry our resolutions into effect. 



But how awful must be the mind which could perform such a task ! The 

 most gifted mathematicians, have, after enormous labor for two centuries, given 

 an approximate solution of the interaction of three gravitating bodies, but they 

 tell us that the methods used would not apply to four bodies, each of which exerted 

 appreciable effects upon the others. How utterly beyond human power it would 

 be to discuss the motions of the millions of chemical atoms contained in a single 

 ounce of matter. Herschel has said that each of these particles is forever solving 

 differential equations, which, if written out, might belt the earth. 



But our imagined ideal mind must deal with the physics of our globe, and 

 the interaction of its myriads of men. The whole phenomena of meteorology 

 must be calculated, not only for every part of the earth, but for all time. The 

 effect of these climatic influences upon each man, and upon the grain or other pro- 

 ductions of his industry, must be determined. The repressing effects of political 

 and social tyranny, and the conditions of their existence ; the refreshing effects of 

 food and sleep, and the circumstances which may sometimes prevent communi- 

 ties or individuals from obtaining enough of them ; the moral influence of men 

 upon each other — to come to smaller matters, the effect of the present address up- 



