"Has it not become clear to them"—meaning: has it not been made clear to them—"how many generations We have destroyed before them," meaning: what has been related regarding those through whom previous nations were destroyed when they denied their messengers. "Walking among their dwellings," meaning: passing through them; some of which are visible, and some of which are not; as in His saying: "Some of them are standing"—that you see—"and mown down"—that you do not see. "Do they not then hear?"—meaning: the polytheists.