Sanity is a funny thing.
It often seems that the more you emphasize your own sanity, rely upon it as a sure thing, compare yours to others, the more likely it is that you are in fact not sane.
On the flip side, it seems to me that questioning one’s own sanity is one of the surest signs that you are NOT insane.
It’s like the Sufi story, wherein everyone drank of the water that came from their wells. One person kept some of this water in storage. One day, the water coming from the wells changed, and everyone who drank it behaved and believed completely different from how they had before. Further, they had no memory of the water that was before, or that the water was ever different. The person who had stored up the old water, however, continued drinking from his stockpile. As a result, he saw that everyone was acting in a manner that they previously would have considered insane; and any attempt he made to convince others that they had changed was met with ridicule. He even offered them some of his stockpiled water, and they considered him mad. As you can imagine, he became very lonely — yet managed to drink only stockpiled water…until one day, he decided he would rather be insane like everyone else, rather than sane and alone. So he drank a cup of water from the wells, and promptly forgot all about his stockpile, and behaved like everyone else. Everyone else, by the way, was relieved that the poor addled and insane fool had finally come to his senses.