Yahweh uses mocking irony to emphasize that Job does not understand light and darkness. Alternate translation: "It is obvious that you do not know, because you were not born when I created them, and you are not very old" (See: [[rc://en/ta/man/jit/figs-irony]])
"for you were already living then." The word "then" refers to the time when light was created and separated from darkness. Alternate translation: "for you were already born when I created them"