To be successful, you should concentrate on the world of companies, not arcane accounting mathematics.
Warren BuffettThe active investors will have their returns diminished by a far greater percentage than will their inactive brethren. That means that the passive group - the "know-nothings" - must win.
Warren BuffettPart of making good decisions in business is recognizing the poor decisions you've made and why they were poor. I've made lots of mistakes. I'm going to make more. It's the name of the game. You don't want to expect perfection in yourself. You want to strive to do your best. It's too demanding to expect perfection in yourself.
Warren BuffettIf you are a professional and have confidence, then I would advocate lots of concentration.
Warren Buffett