"A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects."
-Robert A. Heinlein
ETA: "Before a young man leaves home, there are certain things he should know and certain skills at which he should be adept. We used to kick this around on watch and we covered a lot of ground. What should a young male of 21 know and what should he be able to do? There are no conclusive answers to those questions, but they are certainly worth asking. We agreed upon "civics" or what was called American government. A young man should know how this country is run and how it got that way. He should know the Federalist Papers and de Tocqueville, and he should know recent world history. If he does not know what has been tried in the past, he cannot very well avoid those pitfalls as they come up in the future.Superficialities, of course, are rife.
-Jeff Cooper link