Lessons from Sherlock Pt.2

1. Often what is out of the common is usually a guide rather than a hindrance. In solving a problem of this sort, the grand thing is to be able to reason backwards. 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. Most people, if you describe a train of events to them, will tell you what the results would be. They can put those events together in their minds, and argue from them that something will come to pass. There are few people however, who, if you told them a result, would be able to evolve from their own inner consciousness what the steps were which led up to that result. This power is what I mean when I talk of reasoning backward, or analytically.
2. It is a mistake to confound strangeness with mystery. The most commonplace crime is often the most mysterious, because it presents no new or special features from which deductions may be drawn.
3. The main thing with people when you talk to them in an investigation is to never let them know that their information can be of the slightest importance to you. If you do they will instantly shut up like an oyster. if you listen to them under protest, as it were, you are very likely to get what you want.
4. As a rule, the more bizarre a thing is the less mysterious it proves to be. It is your commonplace, featureless crimes which are really puzzling. Just as a commonplace face is the most difficult to identify.
5. It should be your business to know things. To train yourself to see what others overlook.
6. The most difficult crime to track is one which is purposeless.
7. Crime is common. Logic is rare. Therefore it is upon logic rather than upon crime that you should dwell.
8. 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 vital. Otherwise your energy and attention must be dissipated instead of concentrated.
9. The features given to a man are means by which he shall express his emotions; and you can read a man's train of thought from his features, especially his eyes.
10. Some people without possessing genius have a remarkable power of stimulating it.