
In Seneca’s essay on tranquility, he uses the Greek word euthymia, which he defines as “believing in yourself and trusting that you are on the right path, and not being in doubt by following the myriad footpaths of those wandering in every direction.” It is this state of mind, he says, that produces tranquility. Clarity of vision allows us to have this belief. That’s not to say we’re always going to be 100 percent certain of everything, or...