That is the ego which rises and sinks periodically. But you exist always. That which lies beyond the ego is consciousness - the Self.
Ramana MaharshiCall it by any name, God, Self, the Heart, or the Seat of Consciousness, it is all the same.
Ramana MaharshiIf there is anything besides the Self there is reason to fear? Who sees the second? First, the ego arises and sees objects as external. If the ego does not rise, the Self alone exists and there is no second.
Ramana Maharshi