A pessimist sees only the dark side of the clouds, and mopes; a philosopher sees both sides, and shrugs; an optimist doesn't care. Momentum is wht it wants to gather.
A cup is useful only when it is empty; and a mind that is filled with beliefs, with dogmas, with assertions, with quotations, is really an uncreative mind.
Neverforget the power of silence, that massively disconcerting pause which goes onand on and may at last induce an opponent to babble and backtrack nervously.