It is not sufficient to know what one ought to say, but one must also know how to say it

To Thales the primary question was not what do we know, but how do we know it.

Happiness belongs to the self-sufficient

I wouldn't call it an antagonism as much as one not knowing anything about the other.

One must learn by doing the thing, for though you think you know it, you have no certainty until you try

It is not sufficient that I suceed - all others must fail.