Well, matter is energy E = mc2. There is also space and time or spacetime. Matter, energy, space, and time can be measured, quantified, and described in mathematical terms.
So what is consciousness? Because we are conscious we can discuss these things. But we have not yet quantified consciousness. Erwin Schrdinger believed consciousness was singular. The non dual teachings in Buddhism and Advaita state that consciousness is not its contents. General Semantics points out that a thing is not identical with itself. That is for matter/energy change is constant. So what is birth? and what is death? Two identifiable points in a process. But the process exists before, during, and after those events.
The question is who are you? Who or what dies? or What is death? What ends, and what begins. What we know as the individual life ends. The question about the consciousness that is aware of this is not so clear cut.
Edited by lfen, : pasted the formula E = mc2 in place of my typed E=mcc