Albert Barnes Commentary 1 John 1:2

"(and the life was manifested, and we have seen, and bear witness, and declare unto you the life, the eternal [life], which was with the Father, and was manifested unto us);" — 1 John 1:2 (ASV)

For the life was manifested. It was made manifest or visible to us. He who was the life was made known to men by the incarnation. He appeared among men so that they could see him and hear him. Though originally with God, and dwelling with him (John 1:1–2), yet he came forth and appeared among men. See Barnes on Romans 1:3 and 1 Timothy 3:16.

He is the great source of all life, and he appeared on the earth, and we had an opportunity of seeing and knowing what he was.

And we have seen it. This repetition, or dwelling on the thought, is designed to express the idea with emphasis and is very much in John's style . He is particularly desirous of impressing on them the thought that he had been a personal witness of what the Savior was, having had every opportunity of knowing it from long and familiar interaction with him.

And bear witness. We testify concerning it. John was satisfied that his own character was known to be such that what he said would be believed. He felt that he was known to be a man of truth, and therefore he never doubts that all his statements would be believed (John 21:24; Revelation 1:2; 3 John 1:12).

And shew unto you that eternal life. That is, we declare to you what that life was—what was the nature and rank of him who was the life, and how he appeared when on earth. He here attributes eternity to the Son of God, implying that he had always been with the Father.

Which was with the Father. Always before the manifestation on the earth. (See John 1:1: The word was with God.) This passage demonstrates the pre-existence of the Son of God and proves that he was eternal. Before he was manifested on earth, he had an existence to which the word life could be applied, and that was eternal. He is the Author of eternal life to us.

And was manifested unto us. In the flesh; as a man. He who was the life appeared to men. John's idea evidently is:

1. that the Being here referred to was forever with God;
2. that it was proper before the incarnation that the word life should be given to him as descriptive of his nature;
3. that there was a manifestation of him who was thus called life on earth; that he appeared among men; that he had a real existence here, and not a merely assumed appearance; and
4. that the true characteristics of this incarnate Being could be attested to by those who had seen him and who had been long with him.

This second verse should be regarded as a parenthesis.