It is a question who interpreted this name? The Prophet, or the Evangelist, or some translator? It should be known then, that the Prophet did not interpret it; and what need had the Holy Evangelist to do so, seeing he wrote in the Hebrew tongue? Perhaps that was a difficult and rare word in Hebrew, and therefore needed interpretation. It is more probable that some translator interpreted it, that the Latins might not be perplexed by an unintelligible word.
In this name are conveyed at once the two substances, the Divinity and Humanity in the one Person of the Lord Jesus Christ. He who before all time was begot in an unspeakable manner by God the Father, the same in the end of time was made “Emmanuel,” that is, “God with us,” of a Virgin Mother. This “God with us” may be understood in this way. He was made with us, passible, mortal, and in all things like unto us without sin; or because our frail substance which He took on Him, He joined in one Person to His Divine substance.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).