Phantastes: The Forest Cottage Puzzle

'I fancied I saw a thin blue smoke rising amongst the stems of larger trees in front of me; and soon I came to an open spot of ground in which stood a little cottage, so built that the stems of four great trees formed its corners, while their branches met and intertwined over its roof, heaping a great cloud of leaves over it, up towards the heavens. The cottage, I now saw, was built of the stems of small trees set closely together.... I had just time to see, on the edge of the denser forest, a single large ash-tree, whose foliage showed bluish, amidst the truer green of the other trees around it. A shadow as of a large distorted hand passed slowly over the little blind, and then as slowly returned in the opposite direction. “He dares not come nearer than he is now, for any of those four oaks, at the corners of our cottage, would tear him to pieces; they are our friends. But he stands there and makes awful faces at us sometimes, and stretches out his long arms and fingers, and tries to kill us with fright; for, indeed, that is his favourite way of doing. Pray, keep out of his way to-night.”' - Phantastes, by George MacDonald