What a lovely thing a rose is!"He walked past the couch to the open window and held up the drooping stalk of a moss-rose, looking down at the dainty blend of crimson and green. It was a new phase of his character to me, for I had never before seen him show any keen interest in natural objects. "There is nothing in which deduction is so necessary as religion," said he, leaning with his back against the shutters. "It can be built up as an exact science by the reasoner. Our highest assurance of the goodness of Providence seems to me to rest in the flowers. All other things, our powers, our desires, our food, are all really necessary for our existence in the first instance. But this rose is an extra. Its smell and its color are an embellishment of life, not a condition of it. It is only goodness which gives extras, and so I say again that we have much to hope from the flowers.

Show Holmes a drop of water and he would deduce the existence of the Atlantic. Show it to me and I would look for a tap. That was the difference between us.

For the first time in a very many years, he felt the old vexation, the mingled impatience and pleasure at the world's beautiful refusal to yield up its mysteries without a fight.

It was quite elementary,' returned the detective with a languid gesture of one hand.

You look at me as if I were a conjuror,' Holmes remarked, with a laugh.

Emotional speculation is to deductive reasoning what weeds are to a garden – at first sight they appear to belong, but eventually they obscure that which one hopes will come into bud.

The sensible man,' Crow had said (to Sherlock Holmes), 'don't look to confirm what he already knows -- he looks to deny it. Finding evidence that backs up your theories ain't useful, but finding evidence that your theories are wrong is priceless. Never try to prove yourself right -- always try to prove yourself wrong instead.

How careless of me!" By which she meant that she had deduced that he had found [them] in his pocket and pitied him for needing to be forever in the right.

All people, whether Aspie or neuro-typical are predisposed by their society to make guesses, jump to conclusions and then seek to defend those conclusions, regardless of logic or changing circumstance. This is sloppy, illogical thinking which may not hinder your life too much, under normal circumstances. But if you want to be a great detective, then such thinking will absolutely ruin your chances.

Logical reasoning may be a most convenient means of mental communication for covering short distances, but the curvature of the earth, alas, is reflected even in logic: an ideally rational progression of thought will finally bring you back to the point of departure where you return aware of the simplicity of genius, with a delightful sensation that you have embraced truth, while actually you have merely embraced your own self... anything you might term a deduction already exposes the flaw: logical development inexorably becomes an envelopment.

There's also a possibility that the landlord is in there right now, wearing women's undergarments. Or a drug addict is inside stealing jewelry.Or a boatload of recent Chinese immigrants without a television watching Russia play Finland in hockey and placing bets over beer. You have no idea what's behind that door. You can't just pick the options within your field of vision. Reality comes from everywhere. At best, you can narrow down the likelihoods. But in the end, it's not a matter of deduction. It's a matter of fact. One bullet will kill you if you're stupid or unlucky. So at least don't be stupid

It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts.