Manic depression and lattices

Sweet. Now that I’m public about being manic depressive, I get to write about fun analogies with various aspects of mathematics and computing. Today’s analogy: depression and mania are like least and greatest fixpoints in lattices. To the depressive mind, the world is as bad as it could possibly be given some of the available evidence. (I say “some” because a depressed person tends to ignore a good deal of positive evidence).