Read it through once

The day was overcast, and all that grassy space wherein the Tree stood lay in a soft rich shadow. Joan sat on a natural seat formed by gnarled great roots of the Tree. Her hands lay loosely, one reposing in the other, in her lap. Her head was bent a little toward the ground, and her air was that of one who is lost to thought, steeped in dreams, and not conscious of herself or of the world. And now I saw a most strange thing, for I saw a white shadow come slowly gliding along the grass toward the Tree. It was of grand proportions—a robed form, with wings—and the whiteness of this shadow was not like any other whiteness that we know of, except it be the whiteness of lightnings, but even the lightnings are not so intense as it was, for one can look at them without hurt, whereas this brilliancy was so blinding that it pained my eyes and brought the water into them. I uncovered my head, perceiving that I was in the presence of something not of this world. My breath grew faint and difficult, because of the terror and the awe that possessed me.