ions must, therefore, have been
largely modified and adapted as time went on, and as his finances
allowed. To both, therefore, credit is due for the adaptability evinced
under conditions not always congenial or conducive to the pursuits they
had undertaken.

Although the fact is not definitely stated by Wallace, it may readily be
inferred that the idea of making this the starting-point of a new life
was clearly in his mind; while Darwin simply accepted the opportunity
when it came, and was only brought to a consciousness of its full
meaning and bearing on his future career whilst studying the geological
aspect of Santiago when "the line of white rock revealed a new and
important fact," namely, that there had been afterwards subsidence round
the craters, which had since been in action and had poured forth lava.
"It then," he says, "first dawned on me that I might perhaps write a
book on the geology of the various countries visited, and this made me
thrill with delight. That was a memorable hour to me; and how distinctly
I can call to mind the low cliff of lava, beneath which I rested, with
the sun glaring hot, a few strange desert plants growing near, and with
living corals in the tidal pools at my feet!"[11]

Another point of comparison lies in the fact that at no time did the
study of man or human nature, from the metaphysical and psychological
point of view, appeal to Darwin as it did to Wallace; and this being so,
the similarity between the impression made on them individually by their
first contact with primitive human beings is of some interest.

Wallace's words have already been quoted; here are Darwin's: "Nothing is
more certain to create astonishment than the first sight in his native
haunt of a barbarian, of man in his lowest and most savage state. One
asks: 'Could our progenitors have been men like these--men whose very
signs and expressions are less intelligible to us than those of the
domesticated animals; men who do not possess the instinct of those
animals, nor yet appear to boast of human reason, or at least of arts
consequent on that reason?' I do not believe it is possible to describe
or paint the difference between a savage and civilised man. It is the
difference between a wild and tame animal."[12]

The last words suggest the seed-thought eventually to be enlarged in
"The Descent of Man," and there is also perhaps a subtle suggestion of
the points in which Wallace differed from Darwin when the time