boredom
All our life passes in this way: we seek rest by struggling against certain obstacles, and once they are overcome, rest proves intolerable because of the boredom it produces. We must get away from it and crave excitement.
We think either of present or of threatened miseries, and even if we felt quite safe on every side, boredom on its own would not fail to emerge from the depths of our hearts, where it is naturally rooted, and poison our whole mind.
Man is so unhappy that he would be bored even if he had no cause for boredom, by the very nature of his temperament, and he is so vain that, though he has a thousand and one basic reasons for being bored, the slightest thing, like pushing a ball with a billiard cue, will be enough to divert him.
–Pascal’s Penseés, quoted in Porcupines: A Philosophical Anthology
sarkology 
Pascal: The Pessimist’s Anvil – Too bad he didn’t come before Montaigne. Montaigne might have become a pessimist rather than an optimist. I almost thought: that would’ve been a good thing; habits die hard…