482 ON SPECIES 
truths, why there is an end of the whole matter, and it is 
no use hoping ever to get to any rational explanation of 
origin or dispersion of species — so I hate them. 
January 6, 1859. 
I am determined to start in my investigations on a 
different principle and to try and square all my facts with 
(or arrange them by) the most modern doctrines without 
therefore adhering to or accepting those doctrines. The 
old theory of absolute creations, of single individuals or pairs 
is used up ! Grant them, and what's the use of arguing any 
more ? Grant too that all migration has been effected under 
existing relations of sea and land, and there is an end of 
that matter, we may whistle for another force to effect 
migration, other than the known agency of animals, winds, 
and waters. If we are to assume nothing but these, we are 
stumped ! If the course of migration does not agree with 
that of birds, winds, currents, &c., so much the worse for 
the facts of migration ! No* religious creed could be more 
exigent, exclusive, and repressive. I should be wrong to 
say I disbelieve these doctrines simply because they do not 
explain my facts, so long as they do not contradict them. 
I should be as wrong to say that I believe them so long as I 
think that other doctruaes may explain the facts as well or 
better than these. I now then start on the assumptions : 
(1) That all vegetable forms are in a state of unstable equili- 
brium. (2) That the rate of change and extent of change 
vary at different times and places, depending on physical 
conditions, i.e. on extent of surface to change over and of 
conditions of surface to promote and perpetuate change. 
(3) That the majority of main types of existing forms have 
survived all Geological changes from the Palaeozoic era 
downwards to our time. (4) That during this interval 
many of these type forms have migrated from one hemisphere 
to another, some of them remaining specifically unchanged, 
others generically, others subordinately. (5) That during 
their migration they have expanded and contracted, i.e. 
sometimes thrown off constellations of varieties that (by 
selection) have become new species, at others few, at others 
none. (6) That during some epoch there has been any 
amount of change of land and water. 
This does not touch the aboric^inal condition of all 
