You can only know as far as you go.

As you reach different positions, your understanding shifts accordingly—invest in what you truly understand.

If you've gone further than anyone else in a particular field, that's what you know—your base. When you stay within your base, you win no matter how you fight. That's what it means to understand something.

That little bit you know is your core—and from there, the snowball of your life can start rolling. A snowball needs a core to roll; without one, it just rolls away and disappears.