What is the best explanation of eternity?

You must think of yourself, as passing from eternity to eternity across the narrow bridge of time, as coming from the invisible All-father—made manifest for a brief day and then returning to the bosom of the Infinite. Incarnated first in the lowest phenomena, rising through the dead stone, the living plant, the animal, to the man—then disappearing to the eye of sense and living purely in the spirit.

“I AWOKE!” Conditions of Life on the other Side