ποταμῷ γὰρ οὐκ ἔστιν ἐμβῆναι δὶς τῷ αὐτῷ → it is impossible to step twice in the same river, you cannot step twice into the same rivers
from קוּם; properly, standing (extant), i.e. by implication, a living thing: (living) substance.
