[Even before the “Origin” actually came out, Huxley had begun to act as what Darwin afterwards called his “general agent.”  He began to prepare the way for the acceptance of the theory of evolution by discussing, for instance, one of the most obvious difficulties, namely, How is it that if evolution is ever progressive, progress is not universal?  It was a point with respect to which Darwin himself wrote soon after the publication of the “Origin":—­“Judging from letters...and from remarks, the most serious omission in my book was not explaining how it is, as I believe, that all forms do not necessarily advance, how there can now be simple organisms existing.” (May 22, 1860.)

Huxley’s idea, then, was to call attention to the persistence of many types without appreciable progression during geological time; to show that this fact was not explicable on any other hypothesis than that put forward by Darwin; and by paleontological arguments, to pave the way for consideration of the imperfection of the geological record.

Such were the lines on which he delivered his Friday evening lecture on “Persistent Types” at the Royal Institution on June 3,1859.

However, the chief part which he took at this time in extending the doctrines of evolution was in applying them to his own subjects, Development and Vertebrate Anatomy, and more particularly to the question of the origin of mankind.

Of all the burning questions connected with the Origin of Species, this was the most heated—­the most surrounded by prejudice and passion.  To touch it was to court attack; to be exposed to endless scorn, ridicule, misrepresentation, abuse—­almost to social ostracism.  But the facts were there; the structural likenesses between the apes and man had already been shown; and as Huxley warned Darwin,] “I will stop at no point so long as clear reasoning will carry me further.”

[Now two years before the “Origin” appeared, the denial of these facts by a leading anatomist led Huxley, as was his wont, to re-investigate the question for himself and satisfy himself one way or the other.  He found that the previous investigators were not mistaken.  Without going out of his way to refute the mis-statement as publicly as it was made, he simply embodied his results in his regular teaching.  But the opportunity came unsought.  Fortified by his own researches, he openly challenged these assertions when repeated at the Oxford meeting of the British Association in 1860, and promised to made good his challenge in the proper place.

We also find him combating some of the difficulties in the way of accepting the theory laid before him by Sir Charles Lyell.  The veteran geologist had been Darwin’s confidant from almost the beginning of his speculations; he had really paved the way for the evolutionary doctrine by his own proof of geological uniformity, but he shrank from accepting it, for its inevitable extension to the descent of man was repugnant to his feelings.  Nevertheless, he would not allow sentiment to stand in the way of truth, and after the publication of the “Origin” it could be said of him:—­]