i88o.] The Evolution of Scientific Knowledge . 429 
Newton’s contemporaries were at a high enough level of 
thought to accept his generalisation, which thereupon be- 
came part of the environment which induced subsequent 
though minor generalisations. But this has not always 
been so. Sometimes the conception of a master mind has 
fallen amid conceptions having so little in common with it, 
that its influence has not been felt until the subsequent 
advances of knowledge have caused its re-development, and 
called the attention of the world to a genius who lived 
before his time. Such was the case with some of the gene- 
ralisations of Archimedes, and of Roger Bacon, to mention 
Finally, we may notice the fadt that just as in. the organic 
world we have the highly organised human being existing 
side by side with the lowly organised, entozoon , so too we 
have, in the world of thought, conceptions in some sort in 
harmony with the grandeur of the Cosmos side by side with 
conceptions moulded to the meanest and most trivial facts. 
But there is nothing here at variance with the theory ot 
Evolution. The human being and the entozoon are each 
more or less in harmony with their several environments, 
and any advance in the development of each is such as to 
bring it more clearly in harmony with all the conditions. 
So, too, the conceptions of the philosopher and the clown 
are each more or less in harmony with the environing fadts 
by which they are respeftively surrounded ; and here too, in 
each case, any advance in development is such as to bring 
the conceptions more closely in harmony with the sur- 
rounding fadts. . ,, - ,, I-, 
To this parallel between the organic world and the world 
of thought we may add another. It is now generally ad- 
mitted that the evolution of the individual is a condensed 
epitome of the evolution of the species to which that indivi- 
dual belongs. The evolution, for example, of an individual 
frog from the undifferentiated egg to the complex adult 
epitomises the evolution, through long ages, of frogs from 
simpler forms of life. So, too, does the evolution of the 
conceptions of the individual philosopher epitomise the evo- 
lution of philosophic thought in general. Both in the indi- 
vidual and in the race the discovery of law is itself subjedt 
to law, and, if there be any truth in the views above advo- 
cated, the law to which it is subjedt is the Law of Evolution. 
