72 The Course of Nature. [January, 
coverable by scientific investigation or to be inscrutable. 
Only in the former case have we, as scientific investigators, 
anything to do with the question. The theory, as we have 
to consider it, is in brief this : that the course of events in 
inanimate nature is from time to time modified by invisible 
intelligences just as it is modified by man when he changes 
the course of a river or plants a forest. 
The other explanation of nature is the mechanical 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 effedts are concerned. Each 
state of things is the effedb of the state which immediately 
precedes it, and the cause of that which immediately follows 
it. The course of nature is thus considered as an endlos 
chain, of which the work of science consists in making cit 
the forms of the links, and the modes in which they re 
connected. In this work we have to be concerned with wo 
things : the general laws of nature, as they are familirly 
called, and the fadts or circumstances which determinethe 
operation of these laws. This distinction is most clarly 
seen in human laws. Thou shalt not steal, is a law rthat 
John has stolen, is a fadt. The combined result of tb law 
and the fact is that John is locked up in jail. So tbt all 
bodies near the earth gravitate towards it with r force 
directly as their mass, and inversely as the square c their 
existence from its centre, is a universal law of natur The 
Niagara River and the precipice are facts ; and the ctaract 
is the result. 
But the general explanation of the course of naire, on 
the mechanical theory, is not of this simple kind^ecause 
the laws of nature do not act singly, but in comnation ; 
so that the result of each is modified by the actionf all the 
others which come into play. The law of gravita^n is not 
that all bodies must fall, but only that they tel to fall, 
and, therefore, will fall unless held up by somcsufficient 
opposing force. So long as I support this weht in my 
hand it does not fall, because the force of gra\ation and 
the resistance of my hand neutralise each othc But the 
instant I let go the weight drops, according to ?ertain law 
known as that of uniformly accelerated velocity 
The dodtrine I am endeavouring to elucide is this : 
knowing a few simple laws of nature, of whicgravitation 
is one; knowing also the arrangement of mprial things 
within the field of investigation ; that is, kno^g the fadts, 
we can predidt with unerring certainty what result will 
be : or if we cannot predidt it, it is not b^use of any 
