It is a capital mistake to theorize before you have all the evidence. It biases the judgment.

You are my heart, my life, my one and only thought.

There is no scent so pleasant to my nostrils as that faint, subtle reek which comes from an ancient book.

It is not that I think or believe, but that I know.

It is an old maxim of mine that when you have excluded the impossible, whatever remains, however improbable, must be the truth.

I say, Watson,’ he whispered, ‘would you be afraid to sleep in the same room as a lunatic, a man with softening of the brain, an idiot whose mind has lost its grip?’ ‘Not in the least,’ I answered in astonishment. ‘Ah, that’s lucky,’ he said, and not another word would he utter that night.

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