Let $\mathscr{H}$ be the set of all humans.

Definition: If an element $x$ “cares for” a set $S$, it “cares for” every element in the set.

Remark: If you are a human, and you “care for” humanity, then you must “care for” yourself too.

Proof of Remark: Let $x$ denote you. $x \in \mathscr{H}; x$ “care for” $\mathscr{H} \implies x$ “care for” $x$.