Grace and peace come from the seven Spirits of God (Revelation 1:4). In 4:5, John identifies the seven Spirits with the seven lamps that are before the throne. Spirit is light.

In 5:6, the seven Spirits are identified with the seven eyes of the Lamb. Spirit is not only a light source, but eyes. Eyes in the ancient world were believed to radiate, not merely receive, light. The lamp of the body is the eye. Eyes are of course organs of judgment.

But John probably also has a Hebrew pun in mind. The same word is used for “eye” and “spring,” the “eye-source” from which living water flows. The Lamb is a sevenfold spring of the Spirit, He is Beer-Sheba, the well of oath, the well of seven.