Let me run over the principal steps. We approached the case, you remember, with an absolutely blank mind, which is always an advantage. We had formed no theories. We were simply there to observe and to draw inferences from our observations.

Streams may spring from one source, and yet some be clear and some be foul.

A dog reflects the family life. Whoever saw a frisky dog in a gloomy family, or a sad dog in a happy one? Snarling people have snarling dogs, dangerous people have dangerous ones.

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.

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.

You have a grand gift for silence, Watson. It makes you quite invaluable as a companion.

Crime is common. Logic is rare. Therefore it is upon the logic rather than upon the crime that you should dwell.