To sum up, then, the greater portion of the surface of our country consists of former woodland now reclaimed for the purposes of agriculture, the general aspect of its vegetation altered beyond recognition, though from the fragments left we can still reconstruct with tolerable accuracy its ancient condition, and the flora of which it was composed. In the remaining parts, though drainage, grazing, and other human operations have wrought great changes, the face of the country still wears to a large extent its ancient appearance, and the flora is still in the main that which flourished before human activities began to put their impress upon it. How are we to set about studying this varied vegetation which, in a thousand forms, covers hill and valley? There are several avenues of approach; any one of them, if explored fully, would take us far beyond the limits of the present volume; we shall have to be content with slight venturings along several of them, so as to acquire, in a brief space, as wide a view as we can of the phenomena which our flora displays, and of the problems which it presents. If we view the vegetation as a whole, we may be tempted to enquire first as to its origin and history. We know that plants have existed on the earth for millions of years, but that the plants of past ages were different from those of the present, just as those of the present will ultimately give place to other forms as yet undreamed of: that the vegetation on which we feast our eyes is, in fact, but the momentary expression of a never-ceasing process of life and change. This is the point of view of the geologist, to whom The hills are shadows, and they flow From form to form, and nothing stands; They melt like mist, the solid lands, Like clouds they shape themselves and go.