Half of learning is learning. The other half of learning is unlearning.

Learning begins at the level of the learner.

Happiness extends just as far as study extends, and the more someone studies, the happier he is.

To be learning something new is ever the chief pleasure of mankind .

You know my method. It is founded upon the observation of trifles.

Beyond the obvious facts that he has at some time done manual labour, that he takes snuff, that he is a Freemason, that he has been in China, and that he has done a considerable amount of writing lately, I can deduce nothing else.

I consider that a man's brain originally is like a little empty attic, and you have to stock it with such furniture as you choose. A fool takes in all the lumber of every sort that he comes across, so that the knowledge which might be useful to him gets crowded out, or at best is jumbled up with a lot of other things, so that he has a difficulty in laying his hands upon it.

Problems may be solved in the study which have baffled all those who have sought a solution by the aid of their senses.

There are seventy-five perfumes, which it is very necessary that a criminal expert should be able to distinguish from each other, and cases have more than once within my own experience depended upon their prompt recognition.

Sherlock Holmes had listened with the utmost intentness to the statement of the unhappy schoolmaster. His drawn brows and the deep furrow between them showed that he needed no exhortation to concentrate all his attention upon a problem which, apart from the tremendous interests involved must appeal so directly to his love of the complex and the unusual. He now drew out his notebook and jotted down one or two memoranda.

Sherlock Holmes was, as I expected, lounging about his sitting-room in his dressing-gown, reading the agony column of The Times and smoking his before-breakfast pipe

The conduct of the criminal investigation has been left in the experienced hands of Inspector Lestrade, of Scotland Yard, who is following up the clues with his accustomed energy and sagacity.