With Darwin there is nothing idle, no unquestioned assumption, no glossing over the uncomfortable or inexplicable in the rush to show us that he is right; he has looked into every detail himself, confirming or rejecting what he has heard or imagined, or he has spoken to experts on those details and satisfied himself beyond doubt that they know what they're talking about.
This is not to say that he was in fact right in everything he said, and in every possibility he advanced, but his remarkable mind, and his unswerving dedication to the search for truth, took him as far as it was possible to go at that time.
The book contains hundreds of little anecdotes, incidentally told to support every, apparently minor, observation that he makes. Here I offer you one that I struck me as particularly curious:
'Hardly any faculty is more important for the intellectual progress of man than ATTENTION. Animals clearly manifest this power, as when a cat watches by a hole and prepares to spring on its prey. Wild animals sometimes become so absorbed when thus engaged, that they may be easily approached.
Mr. Bartlett has given me a curious proof how variable this faculty is in monkeys. A man who trains monkeys to act in plays, used to purchase common kinds from the Zoological Society at the price of five pounds for each; but he offered to give double the price, if he might keep three or four of them for a few days, in order to select one. When asked how he could possibly learn so soon, whether a particular monkey would turn out a good actor, he answered that it all depended on their power of attention. If when he was talking and explaining anything to a monkey, its attention was easily distracted, as by a fly on the wall or other trifling object, the case was hopeless. If he tried by punishment to make an inattentive monkey act, it turned sulky. On the other hand, a monkey which carefully attended to him could always be trained.'
Text plagiarised from Project Gutenberg, to whom be life, health and strength.