Here are a couple of quotes from Darwin.
For I am well aware that scarcely a single point is discussed in this volume on which facts cannot be adduced, often apparently leading to conclusions directly opposite to those at which I have arrived. A fair result can be obtained only by fully stating and balancing the facts and arguments on both sides of each question; and this is here impossible.
Origin of Species, Ch. 1, p 1-2
For myself, also, I rejoice profoundly; for, thinking of so many cases of men pursuing an illusion for years, often and often a cold shudder has run through me, and I have asked myself whether I may not have devoted my life to a phantasy
Life and Letters, 1887, Vol. 2, p. 229
"I am quite conscious that my speculations run quite beyond the bounds of true science."
In a letter to Asa Gray, a Harvard professor of biology. Quoted in N.C. Gillespie, 'Charles Darwin and the Problem of Creation' (1979), p. 2 [University of Chicago book]
First, why, if species have descended from other species by fine gradations, do we not everywhere see innumerable transitional forms? Why is not all nature in confusion, instead of the species being, as we see them, well defined?
Origin of Species, Ch. 6, p133
To suppose that the eye with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest degree.
Origin of Species, Ch. 6, p144
If you want more I can dig some more up.
[edit on 26-7-2008 by bakednutz]