A Few Lessons from Sherlock Holmes by Peter Bevelin

• But knowledge doesn't automatically make us wise--the most learned are not the most wise.
• Judgement can do without knowledge but not knowledge without judgement.
• Make sure "facts" are facts--Is it really so? Is this really true? Did this really happen?
• Separate the relevant and important facts from the unimportant or accidental.
• It is of the highest importance in the art of detection to be able to recognize out of a number of facts which are incidental and which are vital. Otherwise your energy and attention must be dissipated instead of being concentrated.
• More information isn't necessarily better information but it may falsely increase our confidence--What is not worth knowing is not worth knowing.
• The world is full of obvious things which nobody by any chance ever observes.
• The eye sees only what it is trained to see.
• "Checklist" routines for critical factors help--assuming I am competent enough to decide what factors are critical and that I can evaluate them.
• It is just these very simply things which are extremely liable to be overlooked.
• Sometimes we overlook that which is most obvious.
• In solving a problem of this sort, the grand thing is to be able to reason backward. That is a very useful accomplishment, and a very easy one, but people do not practice it much. In the everyday affairs of life it is more useful to reason forward, and so the other comes to be neglected.
• Use the simplest means first.
• Which is the simplest, most natural explanation--the one requiring the least assumptions needed to explain the facts?
• There never was a sounder logical maxim of scientific procedure than Ockham's razor...before you try a complicated hypothesis, you should make quite sure that no simplification of it will explain the facts equally well.
• But remember that we see what we are looking for--if we look for similarities, this  is what we see, if we look for the differences, that is what we find.
• The absence of something we expect to see or happen is information and a clue in itself
• Strip away things the don't count and focus on what matters--the core.
• Test our theory--if it disagrees with the facts it is wrong.
• Distance gives perspective--Sometimes we need to remove ourselves from the problem and get a fresh perspective.
• Learn from your mistakes--and learn the general lessons.
• It is easy to be wise after the event, but very difficult to be wiser.
• Don't think about how to get things done, instead ask whether they're worth doing in the first place.
• A lot of misery comes from what we allow ourselves to get dragged into.