A country rapidly passed through under favourable auspices may leave upon us a unity of impression that would only be disturbed and dissipated if we stayed longer. Clear vision goes with the quick foot. Things fall for us into a sort of natural perspective when we see them for a moment in going by; we generalise boldly and simply, and are gone before the sun is overcast, before the rain falls, before the season can steal like a dial-hand from his figure, before the lights and shadows, shifting round towards nightfall, can show us the other side of things, and belie what they showed us in the morning. We expose our mind to the landscape (as we would expose the prepared plate in the camera) for the moment only during which the effect endures; and we are away before the effect can change. Hence we shall have in our memories a long scroll of continuous wayside pictures, all imbued already with the prevailing sentiment of the season, the weather and the landscape, and certain to be unified more and more, as time goes on, by the unconscious processes of thought.