Wisdom is the principal thing; therefore get wisdom; and with all your getting get understanding.
— Bible

If you pick up a starving dog and make him prosperous, he will not bite you. This is the principal difference between a dog and a man.
Mark Twain principals quote

I say quite deliberately that the Christian religion, as organized in its Churches, has been and still is the principal enemy of moral progress in the world.
— Bertrand Russell

We talk on principal, but act on motivation.
— Walter Savage Landor

Good sense is both the first principal and the parent source of good writing.
— Horace