It has been held that before Israel had reached belief in one God (Yahweh) exclusively, it conceded that other nations had their own gods whom it was proper for them to worship (Deut. 32: 8–9; 1 Sam. 26: 19), though Yahweh's superiority to other gods was increasingly asserted (Ps. 86: 8). It is, however, possible that Deutero-Isaiah's unambiguous monotheism developed from an earlier implicit monotheism rather than from henotheism.