The effect, delicate, mysterious, unearthly, cannot be described.
Ethereal gauze...
Visible heat, air-water, and dry sea, Last conquest of the eye...
Sun dust, Aerial surf upon the shores of earth, Ethereal estuary, frith of light....
Bird of the sun, transparent winged.
Do we not see that words fail as pigments do--that the effect is too coarse, since in describing it we put it before the mental eye as something distinctly visible, a thing of itself and separate.

But it is not so in nature; the effect is of something almost invisible and is yet a part of all and makes all things--sky and sea and land--as unsubstantial as itself.

Even living, moving things had that aspect.

Far out on the lowest further strip of sand, which appeared to be on a level with the sea, gulls were seen standing in twos and threes and small groups and in rows; but they did not look like gulls--familiar birds, gull-shaped with grey and white plumage.

They appeared twice as big as gulls, and were of a dazzling whiteness and of no definite shape: though standing still they had motion, an effect of the quivering dancing air, the "visible heat"; at rest, they were seen now as separate objects; then as one with the silver sparkle on the sea; and when they rose and floated away they were no longer shining and white, but like pale shadows of winged forms faintly visible in the haze.
They were not birds but spirits--beings that lived in or were passing through the world and now, like the heat, made visible; and I, standing far out on the sparkling sands, with the sparkling sea on one side and the line of dunes, indistinctly seen as land, on the other, was one of them; and if any person had looked at me from a distance he would have seen me as a formless shining white being standing by the sea, and then perhaps as a winged shadow floating in the haze.