Michel de Montaigne, the 16th-century French writer, tells us in one of his Essays that we cannot be deemed happy until after we die, because how we die might void any or all of the happiness we experienced in life. A great king might be executed by one of his rivals, after having his lands seized and all of his heirs killed. By contrast, an “execrable and ill-famed” man might leave this mortal coil “in all respects perfectly reconciled” to those around him.

If we can only “really” understand a life after it is over, we are apparently doomed never to understand our own. Any insight we might at some point gain into ourselves is only temporary; standing always to be revised. Examples from literature might seem to bear this point out. Most novels don’t bother trying to descri...