Tiphareth is the first of the higher spheres on the tree. It is the true-self, or the higher-self.
Consider - Tiphareth is not Malkuth, we are not our bodies.
Tiphareth is not Yesod, although we have a past - we are something else, we can overcome the past and grow in new directions.
Tiphareth is not Hod, we think yet our thoughts are about outside stuff. WE think. Thinking is something we do, in the same way as we sleep and eat.
Tiphareth is not Netzach, although our feelings for things exist they are still empherial. It is possible to be so numb to the world that we feel nothing - yet we continue to exist.
Tiphareth is that thing which has a body, has a past, has thoughts and has feelings. Once we have moved away from these things the sense of what is there is Tiphareth.