82 HAECKEL: HiS LIFE, WORK, AND COMPANIONS 
own observations, Darwin, after his five year’s voyage, 
returned to England a confirmed uniformitarian in geology. 
During his expedition Darwin kept in mind the subject 
destined to be his life work—the transmutation of species. 
In the Pampas he noted great fossil animals, armour-clad 
after the inanner of the armadillos, one species of which is 
scarcely afoot long; and he had seen in going southwards 
that closely allied animals replace one another. And soon 
after his return home he commenced to compile note-books 
on the samesubject. The first of these books was opened in 
1837, and facts were collected wholesale, for he says: “‘ I 
worked on true Baconian principles.” 
Godwin, in his ‘‘ Political Justice,’’? published in 1793, 
pictured an ideal state of society free from crime and misery ; 
and at the close of his book he controverted the teaching of 
Robert Wallace, that the advantages of such a community 
would be nullified by the excessive population that would 
ensue. Five years afterwards Malthus, in his famous 
essay, restated the objections of Wallace with greater force. 
His more comprehensive argument, tersely put, was that 
population increases in a geometrical and means of subsist- 
ence in an arithmetical ratio; and that vice and crime are 
but necessary checks on that increase of numbers. In the 
autumn of 1838, fifteen months after Darwin hegan his 
systematic inquiry, he chanced to read ‘‘ Malthus on Popu- 
lation.’”’ He had already learned much as to the struggle 
for existence going on in the world of life. and, as he read, 
the thought struck him that under such stress favourable 
variations would tend to be preserved, and those unfavour- 
able to be destroyed. So the reading of Malthus afforded a 
provisional theory aiding him to gather in facts, and gave 
him heart to continue his labours. 
As his mass of facts accumulated, his views took more 
definite shape. But not till 1842, when he had worked 
five years, did he indulge in the satisfaction of a slight 
pencil-written abstract of his theory. What he wrote 
