In practice, there’s always a golden mean between telling nobody and telling everybody — and that’s a company. The best entrepreneurs know this: every great business is built around a secret that’s hidden from the outside.

Every university believes in “excellence,” and hundred-page course catalogs arranged alphabetically according to arbitrary departments of knowledge seem designed to reassure you that “it doesn’t matter what you do, as long as you do it well.” That is completely false. It does matter what you do. You should focus relentlessly on something you’re good at doing, but before that you must think hard about whether it will be valuable in the future.

A board of three is ideal. Your board should never exceed five people, unless your company is publicly held. (Government regulations effectively mandate that public companies have larger boards — the average is nine members.) By far the worst you can do is to make your board extra large. When unsavvy observers see a nonprofit organization with dozens of people on its board, they think: “Look how many great people are committed to this organization! It must be extremely well run.” Actually, a huge board will exercise no effective oversight at all; it merely provides cover for whatever microdictator actually runs the organization. If you want that kind of free rein from your board, blow it up to giant size. If you want an effective board, keep it small.