Isaiah 8:3 - Albert Barnes' Notes on the Bible

Then said the Lord ... - The name thus given was to be emblematic of a particular event - that Assyria would soon take away the spoil of Damascus and Samaria. It is not remarkable that the name Immanuel should also be given to the same child, as signifying the presence and protection of God in defending the nation from the invaders; see the notes at Isaiah 7:14-15. Calvin thinks that all this passed in a vision before the prophet; but it has every mark of being a literal narrative of the birth of a son to Isaiah; and without this supposition, it is impossible to understand the account contained here.