iS79-] 
The Course of Nature, 
73 
quality of the thing itself, but only because of the insuffi- 
ciency of our powers. Moreover, these results will be, as it 
were, another layer of fadfs from which it is possible to pre- 
ditft new results to follow them, and so on without limit, 
unless some force from without intervene to change the 
course. If we include the whole of nature in our field, no 
outside fadts can come in, and her course, therefore, admits 
of being predicted with entire certainty from beginning 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, respedfing the relations of the 
two classes of causes, or supposed causes, which I have 
described. 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 accordance with mechanical laws, at least so far as 
the phenomena are concerned, no one ever knowingly denied. 
But it was thought that the adtion 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 adtion of those beings who were 
modifying the course of nature in order to compass their 
ends. 
As illustrating this, I might commence with the age of 
image worship, when the fate of the individual is supposed 
to be at the mercy of certain spiritual entities, symbolised 
by forms of wood, stone, or wax. But, leaving out of con- 
sideration ideas so different from those which prevail among 
us, let us come nearer home. It is not many generations 
since men who knew that the regular course of nature went 
on in accordance with mechanical laws believed, neverthe- 
less, that occurrences of a terrific or extraordinary charadter 
were specially brought about to compass some end of Pro- 
vidence. Not only so, but, what is most essential to our 
theme, this end was supposed to be a scrutable one. The 
motions of stars and planets had gone on from age to age, 
until no new aspedt of them inspired alarm. But a comet 
was looked upon as a messenger specially sent to give 
warning of a coming calamity. The scrutable end was, in 
this case, the warning of mankind. Ordinary cases of sick- 
ness and accident, whatever their result, always have been 
looked upon as a part of the regular course of events. But it 
