The common definition of personality is only useful in describing the mind, its operation, and its interface to the material manifestation, and that definition is deceptive. Mind is another covering of jiva, mind has a locus (the brain, although that gets a little fuzzy these days) within the covering shell of the material body, all covered by karmic conditioning. The jiva is outside/underlying all of those ephemeral coverings, but it is NOT ephemeral.