Fra Angelico and the Green Door garden

As discussed in this post, the H. G. Wells story "The Door in the Wall" features a green door in a white wall that leads into an enchanted garden. In Green Doors by Ethel Cook Eliot, Green Doors is the name of a house which also has gardens of such beauty as to suggest the supernatural.

"Clare won’t let them cut the grass here," Petra explained. "Any objection to wading?" Lewis had none and followed the girl around the side of the little house and came to an uncovered piazza at the back. Ignoring the several chairs arranged with an eye to the view there, they sat down side by side on the edge of the piazza boards. From under their feet wide sweeps of June fields surged away in many-colored rippling waves. White and yellow daisies, red and white clovers, golden buttercups, orange devil's-paintbrush, and sparkling sun-soaked grass dazzled Lewis' eyes against the view of river and blue hills beyond.

"Paradise will be a June field like this," he thought, "with the saints reunioning while the angels dance." He was thinking of Fra Angelico’s "Last Judgment," the detail of the left corner. -- "Petra and I seem to have arrived somewhat ahead of time, though, -- and, God knows, without our crowns! . . ."

This is the painting Lewis is referring to:

Today I encountered a reference to Fra Angelico in an English grammar textbook.