John 1:4 "In him was life; and the life was the light of men."
Here is a continued unfolding of this unique, distinct Being within the Godhead. It will be beneficial at this point to consider a couple of points.
In John 4:24, when talking to the woman at the well, Jesus told her:
"God [is] a Spirit: and they that worship him must worship [him] in spirit and in truth." God’s essence is pure Spirit.
Secondly, in 1Timothy 6:16:
"Who only hath immortality, dwelling in the light which no man can approach unto; whom no man hath seen, nor can see: to whom [be] honor and power everlasting. Amen."
Immortality is self-subsistence. This is how God revealed Himself to Moses.