The matter is life.
Science can only tell us that when the muscle of the heart no longer functions,
Yet Science has still not officially decided where life begins (or else the abortion debate
would be moot).
Regardless of religious faith we are socialized to believe life—the functioning heart—is sacred and globally, laws protect it.
Between the time life begins (whenever that is) and the time it ends (once the heart stops functioning permanently) the heart’s performance makes all kinds of other stuff possible: creating, caring, deciding.
It’s probably only that those opportunities are possible that we bother to “live;” when they’re not anymore, that we let go.