i879-] 
The Course of Nature, 
6g 
science offers its highest rewards to him who will overthrow 
and supplant its best-established and most widely received 
theories. Thus the names of the men who disproved the 
theory of epicycles in astronomy, and the dodtrine of phlo- 
giston in chemistry, occupy the most honourable positions 
in the history of science. Of course, no such thing as 
authority in science has anything more than a provisional 
recognition. If a man of good repute says that he has 
investigated a certain subjedt and reached a certain result, 
the latter may be accepted on his authority, in the absence 
of other evidence. But this gives no reason at all why any 
one else should not reach a different result, and it would be 
no argument at all to cite the mere authority of the first 
against the second. In case of a discrepancy of this kind, 
the whole question would have to be re-investigated. The 
didtum, “ It is written,” has no terror whatever for the 
investigator of nature ; he can recognise no authority for 
any feature in the course of nature, except nature herself as 
he sees her. 
These principles are of so much importance in the philo- 
sophy of science that I may be pardoned for viewing them 
in yet another light. In reading those discussions with 
scientific men on certain theories recently advanced by the 
more advanced students of philosophic biology into which 
the representatives of theology sometimes enter, I have 
often noticed that if the representative of science propounds, 
discovers, or^brings forward any fadt or principle which 
seems to tell against his side of the question, the other calls 
it an “ admission,” or “ concession,” just as if his opponent 
had first seledted his side for the love of it, and was then 
unwilling to concede or admit anything which might mili- 
tate against it. Now, to go into the philosophy of the sub- 
jedt a little deeper than heretofore, allow me to say that the 
man of science professes no ability to recognise truth on 
sight, as he would recognise a house or an animal. The 
question whether any given proposition is or is not true, is 
necessarily to be decided by the human judgment, co- 
ordinating all the fadts which bear upon it. There is no 
such thing as a revelation of scientific truths, and even if 
one should claim that there was, the admission or rejedtion 
of the claim would be an adt of the judgment, which thus 
becomes the ultimate arbiter in any case. Hence a propo- 
sition is to be proved probable or true, not by anything in 
itself, but by a more or less long and painful examination 
of the evidence for and against it. Everything that can be 
found to militate in favour of it is put into one scale, and 
