Darwin's skill was transmuting his own blurred imagination to supposed "facts" about form, e.g.:
He who will go thus far, if he find on finishing this treatise that large bodies of facts, otherwise inexplicable, can be explained by the theory of descent, ought not to hesitate to go further, and to admit that a structure even as perfect as the eye of an eagle might be formed by natural selection, although in this case he does not know any of the transitional grades.The Origin of Species (I.e., the origin of form in life forms.)
After a Darwinist is through going through all of Nature sifting it for similarities to imagine historical claims about while rejecting differences that falisfy their imaginings, then they claim that the rest ought to be imagined! As if they had not done enough imagining about history already? Darwin may be lost in his own imagination about history yet the result is that he simply lies about what he is doing when it comes to hypothetical imagination vs. theoretical reasoning, as ironically he continues in the next sentence:
His reason ought to conquer his imagination; though I have felt the difficulty far too keenly to be surprised at any degree of hesitation in extending the principle of natural selection to such startling lengths.(Ib., emphasis added) Yet if reason had conquered his imagination then he wouldn't be asking others to imagine that natural selection can be extended in nearly infinite ways, nor that it has some sort of "sight" by which it can "pick" different forms to draw out images. It seems to me that Darwin is explaining what is going on in his own head as he picks forms and patterns of imagery that suit his further imaginations that culminate with the claim being we should imagine natural selection with near infinite capacities. This is why I cannot do anything but call the imaginary mind of this man a liar when it claims that "reason must conquer imagination." Not to worry, I didn't attack the man, just the mind that he seems to have lost somewhere in his own imagination.
Given the reliance of such a mind on imagination, even the supposed possiblity of the falsification of its ideas are clearly impossible being that they are based on a possible failure of its own imagining. And why would a mind want to imagine its own failure? E.g.:
If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down. But I can find out no such case.(Ib. emphasis added) He just can't admit that he's the one imagining numerous, successive, slight modifications and instead merges and mixes his own imaginings in with supposed actual cases. I think it is telling that to remain atheistic when it comes to Life and the fundamental origins of its form people have to engage in Darwininan "reasoning" in which you work your own imagination in to count as fact to such a point that even your supposed falsification is clearly a negative argument of impossiblity that has nothing to do with the facts. No one will ever be able to prove a negative that is rooted in your own imagination. And of course it is impossible for you yourself to "imagine" a sequence in which your own theory absolutely breaks down.
But that's only because it was your own hypothetical excrement* to begin with.
*Although "unclean" excrement does have this way of being turned back to forms of life, it is not the origins or cause of form. Maybe there is some metaphoric Excrement that considers being equal with that which is truly the genesis of form something to be grasped. Then I suppose some might ask, "But who excreted the Excrement?" But that's another post.