“We have seen his glory, glory as of the only Son from the Father.”
In the Old Testament, the Hebrew word that is normally translated as glory is kabod, which literally means "weight" or "heaviness." It is used to express importance, honor, and majesty. The New Testament Greek word is doxa which implies honor, renown, and splendor.
In this video, John Piper makes the argument that even compared to eye-witnesses of Jesus, you're at no disadvantage if you want to see Jesus' glory today.
John 1:14 14 And the Word became flesh and dwelt among us, and we have seen his glory, glory as of the only Son from the Father, full of grace and truth.
John 17:20 20 “I do not ask for these only, but also for those who will believe in me through their word...