What was Darwin Thinking?

Kamil Ahsan looks at the documentation to figure out Darwin's method as he developed the theory of natural selection. Ahsan's conclusion:

At some point it must be recognized that evolution by natural selection was not the result of years of observation in which Darwin had no working hypothesis, but instead years of observations geared towards designing proofs for a hypothesis based on little more than a hunch; a frantic search on ‘the species question’ that ensued as little more than a rat race with Alfred Russell Wallace."

I'm never convinced by these arguments that a particular person only used one mode of thought to get where they needed to go, but the conclusion ultimately reached here is precisely in agreement with that concept--that the search is one guided by both theory and observation.