History

There are certain lessons to be learnt from history.
How wars are lost
How wars are won

Why a civilization fell,
how doing something right can be the best thing you ever did

If you can't learn from the past then you're doomed to forever repeat your mistakes.
How I will never lend a certain someone money because they start coming up with all sort of excuses how they can't pay you
How I will never expect anything from certain people because those expectations would be unreasonable and unattainable by their standards
How I will not draw/imagine patterns where there are none.

Those are the lessons you learn amongst others.
So who says history isn't important?
;)