We can't say that all lives matter until we start treating all lives as if they all mattered. As if each was the most precious resource we have. As if losing one of us is losing all of us. “Oh,” a professor says in the play W;t, “it’s an allegory of the soul!” And it is.
Do you have a soul? We have to start with what a soul is, which should be easy, it's only four letters, but the thing is, it's not easy, even if it were three letters. We don't have a unilateral definition of the soul. We don't know where the soul "lives" in the body. We don't know if the soul is separate from our earthly experiences. All we have is a hopeful maybe.