‎A change of work is the best rest.

He had never seen a woman doctor before, and his whole conservative soul rose up in revolt at the idea. He could not recall any biblical injunction that the man should remain ever the doctor and the woman the nurse, and yet he felt as if a blasphemy had been committed.

[Sherlock Holmes:] The temptation to form premature theories upon insufficient data is the bane of our profession.

I am a brain, Watson. The rest of me is a mere appendix.

Some people's affability is more deadly than the violence of coarser souls.

I am the most incurably lazy devil that ever stood in shoe leather.

While the individual man is an insoluble puzzle, in the aggregate he becomes a mathematical certainty. You can, for example, never foretell what any one man will be up to, but you can say with precision what an average number will be up to. Individuals vary, but percentages remain constant. So says the statistician.