An optimist will tell you the glass is half-full; the pessimist, half-empty; and the engineer will tell you the glass is twice the size it needs to be.
We look for some reward of our endeavors and are disappointed that not success, not happiness, not even peace of conscience, crowns our ineffectual efforts to do well. Our frailties are invincible, our virtues barren; the battle goes sore against us to the going down of the sun.
Progress is Providence without God. That is, it is a theory that everything has always perpetually gone right by accident. It is a sort of atheistic optimism, based on an everlasting coincidence far more miraculous than a miracle.
The vanishing, volatile froth of the present which any shadow will alter, any thought blow away, any event annihilate, is every moment converted into the adamantine.
The most common cause of low prices is pessimism - some times pervasive, some times specific to a company or industry. We want to do business in such an environment, not because we like pessimism but because we like the prices it produces. It's optimism that is the enemy of the rational buyer.