by express; they have an alarum aloft, and do not sleep. From within some little grove of other trees a single poplar makes a slight sign; or a long row of poplars suddenly sweep the wind. They are salient everywhere, and full of replies. They are as fresh as streams.
It is difficult to realize a drought where there are many poplars. And yet their green is not rich; the coolest have a colour much mingled with a cloud-grey. It does but need fresh and simple eyes to recognize their unfaded life. When the other trees grow dark and keep still, the poplar and the aspen do not darken—or hardly—and the deepest summer will not find a day in which they do not keep awake. No waters are so vigilant, even where a lake is bare to the wind.
When Keats said of his Dian that she fastened up her hair "with fingers cool as aspen leaves," he knew the coolest thing in the world. It is a coolness of colour, as well as of a leaf which the breeze takes on both sides—the greenish and the greyish. The poplar green has no glows, no gold; it is an austere colour, as little rich as the colour of willows, and less silvery than theirs. The sun can hardly gild it; but he can shine between. Poplars and
