Problems may be solved in the study which have baffled all those who have sought a solution by the aid of their senses. To carry the art, however, to its highest pitch, it is necessary that the reasoner should be able to use all the facts which have come to his knowledge; and this in itself implies, as you will readily see, a possession of all knowledge, which, even in these days of free education and encyclopaedias, is a somewhat rare accomplishment.

You mentioned your name as if I should recognize it, but beyond the obvious facts that you are a bachelor, a solicitor, a freemason, and an asthmatic, I know nothing whatever about you.

"Recognising, as I do, that you are the second highest expert in Europe" "Indeed, sir! May I inquire who has the honour to be the first?" Asked Holmes, with some asperity. "To the man of precised, scientific mind the work of Monsieur Bertillon must always appeal strongly." "Then had you not better consult him?" "I said, sir, to the precisely scientific mind. But as a practical man of affairs it is acknowledged that you stand alone. I trust, sir, that I have not inadvertently--" "Just a little," said Holmes.

It is of the highest importance in the art of detection to be able to recognise out of a number of facts which are incidental and which are vital.

His ignorance was as remarkable as his knowledge. Of contemporary literature, philosophy and politics he appeared to know next to nothing... My surprise reached a climax, however, when I found incidentally that he was ignorant of the Copernican Theory and of the composition of the Solar System.

An absence of antecedents and of relatives is sometimes an aid rather than an impediment to social advancement . . .

You will ruin no more lives as you ruined mine. You will wring no more hearts as you wrung mine. I will free the world of a poisonous thing. Take that, you hound, and that! - and that! - and that! - and that!