Of all ruins, that of a noble mind is the most deplorable.

The sky was of the deepest blue, with a few white, fleecy clouds drifting lazily across it, and the air was filled with the low drone of insects or with a sudden sharper note as bee or bluefly shot past with its quivering, long-drawn hum, like an insect tuning-fork.

By a man's finger-nails, by his coat-sleeve, by his boots, by his trouser-knees, by the callosities of his forefinger and thumb, by his expression, by his shirt-cuff — By each of these things a man's calling is plainly revealed. That all united should fail to enlighten the competent inquirer in any case is almost inconceivable. You know that a conjurer gets no credit when once he has explained his trick; and if I show you too much of my method of working, you will come to the conclusion that I am a very ordinary individual after all.

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. [...] It is a mistake to think that that little room has elastic walls and can distend to any extent. [...] It is of the highest importance, therefore, not to have useless facts elbowing out the useful ones.

My mind rebels at stagnation. Give me problems, give me work, give me the most abstruse cryptogram, or the most intricate analysis, and I am in my own proper atmosphere. But I abhor the dull routine of existence. I crave for mental exaltation.

If in 100 years I am only known as the man who invented Sherlock Holmes then I will have considered my life a failure.

He foresaw that she would be very much more useful to him in the character of a free woman.