THE COURSE OF NATURE. 



485 



the explanation of natural phenomena by design, 

 has two distinct forms — the scientific and the theo- 

 logical. These forms are not antagonistic ones ; 

 the one is held by scientific men, and the other 

 by theologians ; for, as you may well know, the 

 scientific form is the one in which scientific men 

 almost universally reject the teleological theory, 

 while they have nothing to say against the other 

 form. The forms refer only to the fields to which 

 the theory may belong — the scientific and the 

 theological. The distinction turns on whether 

 we suppose the ends which the Creator has in 

 view to be discoverable by scientific investigation 

 or to be inscrutable. Only in the former case 

 have we, as scientific investigators, anything to 

 do with the question. Now, as we shall more 

 fully see hereafter, the number of ends supposed 

 to be scrutable has constantly diminished, and 

 the theory of design on the scientific side has 

 narrowed its scope in proportion. 



The only scrutable end which Nature is now 

 supposed to have in view is the good of living 

 creatures, and especially of man ; and even in 

 this field we know so little about what is good 

 for us individually that we here have only a slight 

 clew to the result. On the other hand, the num- 

 ber of events which, directly or indirectly, inter- 

 est us is so great that this slight clew may be 

 supposed to lead to many knowable results, if we 

 once admit the theory. 



The other explanation of Nature is the me- 

 chanical one. It assumes that her processes go 

 on in accordance with certain laws, which admit 

 of being fully comprehended by the human mind 

 so far as their effects are concerned. Each state 

 of things is the effect of the state which immedi- 

 ately precedes it and the cause of that which im- 

 mediately follows it. The course of Nature is 

 thus considered as an endless chain, the work 

 of science consisting in making out the forms 

 of the links and the modes in which they are con- 

 nected. In this investigation we have to be gov- 

 erned by two things — the general laws of Na- 

 ture, as they are familiarly called, and the facts 

 or circumstances which determine the operation 

 of these laws. This distinction is most clearly 

 6een in human laws. Thou shalt not steal is a 

 law. That John has stolen is a fact. The com- 

 bined result of the law and the fact is, that John 

 is locked up in jail. So that all bodies near the 

 earth gravitate toward it with a force directly as 

 their mass and inversely as the square of their 

 distance from its centre is a universal law of 

 Nature. The Niagara River and the precipice 

 are facts, and the cataract is the result. 



But the general explanation of the course of 

 Nature on the mechanical theory is not of this 

 simple kind, because the laws of Nature do not 

 act singly, but in combination ; so that the result 

 of each is modified by the action of all the others 

 which come into play. The law of gravitation is 

 not that all bodies must fall ; but only that they 

 tend to fall, and therefore will fall unless held 

 up by some sufficient opposing force. So long as 

 I support this weight in my hand it does not fall, 

 because the force of gravitation and the resist- 

 ance of my hand neutralize each other. But the 

 instant I let go, the weight drops, according to a 

 certain law known as that of uniformly acceler- 

 ated velocity. 



The doctrine I am endeavoring to elucidate is 

 this : Knowing a few simple laws of Nature, of 

 which gravitation is one; knowing also the ar- 

 rangement of material things within the field of 

 investigation — that is, knowing the facts — we can 

 predict with unerring certainty what the result 

 will be. Or, if we cannot predict it, it is not be- 

 cause of any quality of the thing itself, but only 

 because of the insufficiency of our powers. More- 

 over, these results will be, as it were, another 

 layer of facts, from which it is possible to pre- 

 dict new results to follow them, and so on with- 

 out limit, unless some facts from without inter- 

 vene to change the course. If we include the 

 whole of Nature in our field, no outside facts can 

 come in ; and her course, therefore, admits of be- 

 ing predicted with entire certainty from begin- 

 ning to end. 



Now, the point which I wish to bring to your 

 attention is the revolution which modern science 

 has brought to pass, in the opinions of mankind, 

 respecting the relations of the two classes of 

 causes, or supposed causes, which I have de- 

 scribed. 



That all events could be explained on teleo- 

 logical principles it is not likely that any one 

 ever supposed. That the falling of heavy bodies, 

 the running of rivers, the changes of seasons, and 

 the revolutions of the heavens, were all in accord- 

 ance with mechanical laws, at least so far as the 

 phenomena are concerned, no one ever knowingly 

 denied. But it was thought that the action of 

 these causes was from time to time modified by 

 the introduction of causes of the teleological 

 class, just as a rock might be kept from falling 

 by the force of cohesion. The general rule has 

 been, that the more ignorant the age the more 

 minute and immediate was supposed to be the 

 action of those beings who were modifying the 

 course of Nature in order to compass their ends. 



