I owe much to my friends; but, all things considered, it strikes me that I owe even more to my enemies. The real person springs life under a sting even better than under a caress.
It is not always by plugging away at a difficulty and sticking to it that one overcomes it; often it is by working on the one next to it. Some things and some people have to be approached obliquely, at an angle.
Know thyself. A maxim as pernicious as it is ugly. Whoever studies himself arrest his own development. A caterpillar who seeks to know himself would never become a butterfly.