ישעיהו, פרק מ״ו, פסוק ט׳

Looking back at ancient history serves as the ultimate proof of God's absolute unity. The prophet urges the people to reflect deeply on the earliest events of the past. While some view this as a general call to remember the miracles, wonders, and mighty deeds performed in ancient times [מצודת דוד, מלבי״ם], others point specifically to the Exodus from Egypt. During that defining moment, God freed the Israelites against the will of their captors and passed judgment upon the Egyptian deities [רד״ק]. Regardless of the specific focus, reflecting on these past events is what provides a clear, undeniable recognition of God's exclusive power [אבן עזרא, רש״י].

This historical memory naturally leads to a firm and absolute conclusion designed to entirely reject false systems of belief. A double declaration is made to address different theological errors. First, the assertion that there is no other God strips away any belief in polytheism, eliminating the idea that there are multiple gods, independent powers, or competing spiritual forces at work in the world. Second, the absolute denial that anything exists like Him is meant to uproot the concept of dualism, completely rejecting the belief in two separate divine domains [מלבי״ם].