More accurately, that everything comes from and is shunyata (emptiness). Emptiness is also not nothingness, which is a different thing. Emptiness (of svabhava: "self existence") means infinite potentiality, since it is what makes anything possible. Nagarjuna proved that if something is not empty of self existence then it would annihilate itself and be unable to have any impact on our reality. The only reason that things can (seem to) exist is because nothing exists in itself, so it is impossible to distinguish between say, an apple, and the entire universe.