Depend upon it there comes a time when for every addition of knowledge you forget something that you knew before. It is of the highest importance, therefore, not to have useless facts elbowing out the useful ones.

It's a very cheery thing to come into London by any of these lines which run high and allow you to look down upon the houses like this." I thought he was joking, for the view was sordid enough, but he soon explained himself. "Look at those big, isolated clumps of buildings rising up above the slates, like brick islands in a lead-coloured sea." "The board-schools." "Light-houses, my boy! Beacons of the future! Capsules with hundreds of bright little seeds in each, out of which will spring the wiser, better England of the future.

...Holmes, who loathed every form of society with his whole Bohemian soul, remained in our lodgings in Baker Street, buried among his old books, and alternating from week to week between cocaine and ambition, the drowsiness of the drug, and the fierce energy of his own keen nature.

If you had killed Watson, you would not have got out of this room alive.

Well, sir, let us do what we can to curtail this visit, which can hardly be agreeable to you, and is inexpressibly irksome to me.

There seems to me to be absolutely no limit to the inanity and credulity of the human race. Homo Sapiens! Homo idioticus!

At the moment our human world is based on the suffering and destruction of millions of non-humans. To perceive this and to do something to change it in personal and public ways is to undergo a change of perception akin to a religious conversion. Nothing can ever be seen in quite the same way again because once you have admitted the terror and pain of other species you will, unless you resist conversion, be always aware of the endless permutations of suffering that support our society.