According to Blake Ezekiel once acted out a bizarre symptom of the prospects of the Israelites, lying for an inordinate period of time on his left side, then another period on his right. Mr. Blake had a conversation with him about that and asked him why he had done it; the answer came clearly: "the desire of raising other [people] into a perception of the infinite" (Marriage of Heaven and Hell, Plate 13.
Who can doubt that William actually had that interview with Zeke? But if truth be known, that desire became the agenda for Blake's life, and perhaps the generic life purpose of every true prophet.
He saw things that most of us don't, and he urgently needed to show them to us, to show us how to see them.
There are many kinds of seeing and many levels of consciousness, but with the natural proclivity to resort to the dialectic we might say there are two:
1. The sense-based, natural, materialistic time and space consciousness (Blake called this Ulro; Jesus called it Hell).
2. Vision, coming forth from the inner man, the Light, the Now. It's a different kind of consciousness, a perception of the infinite (Blake called it Eden; Jesus called it the Kingdom of Heaven or the Kingdom of God).
Jesus showed us with his life how to live eternally; and he told us we could do it. Blake did it, periodically at least, and like Jesus he wanted us to share that heavenly gift.
He called it Vision; that's what he lived for, those eternal moments were all that matters. If you can't do it continuously, then you can talk about it, write about it, draw it, paint it. He did (and you can) show us how to see.
The above came from the beginning of my Primer.