States of profound happiness, like all other forms of intoxication, are apt to befuddle the wits; intense enjoyment of the present always makes one f… - Stefan Zweig

The avaricious are thrifty with time as well as money.

Unhappiness makes people vulnerable, incessant suffering unjust. Just as in the relations between a creditor and a debtor there is always an element of the disagreeable that can never be overcome, for the very reason that the one is irrevocably committed to the role of giver and the other to that of receiver, so in a sick person a latent feeling of resentment at every obvious sign of consideration is always ready to burst forth.

Someone who's on top of the world isn't much of an observer: happy people are poor psychologists. But someone who's troubled about something is on the alert. The perceived threat sharpens his senses - he takes in more than he usually does.