When, standing in the village street, your eye travels up that white band, you can distinctly make out even at that distance a small, solitary tree standing near the summit--an old thorn with an ivy growing on it. My walks were often that way, and invariably on coming to that point I would turn twenty yards aside from the road to spend half an hour seated on the turf near or under the old tree. These half-hours were always grateful; and conscious that the tree drew me to it I questioned myself as to the reason. It was, I told myself, nothing but mental curiosity: my interest was a purely scientific one. For how comes it, I asked, that a thorn can grow to a tree and live to a great age in such a situation, on a vast, naked down, where for many centuries, perhaps for thousands of years, the herbage has been so closely fed by sheep as to have the appearance of a carpet, or newly mown lawn? The seed is carried and scattered everywhere by the birds, but no sooner does it germinate and send up a shoot than it is eaten down to the roots; for there is no scent that attracts a sheep more, no flavour it has greater taste for, than that of any forest seedling springing up amidst the minute herbaceous plants which carpet the downs. The thorn, like other organisms, has its own unconscious intelligence and cunning, by means of which it endeavours to save itself and fulfil its life. It opens its first tender leaves under the herbage, and at the same time thrusts up a vertical spine to wound the nibbling mouth; and no sooner has it got a leaf or two and a spine than it spreads its roots all round, and from each of them springs a fresh shoot, leaves and protecting spine, to increase the chances of preservation. In vain! the cunning animal finds a way to defeat all this strategy, and after the leaves have been bitten off again and again, the infant plant gives up the struggle and dies in the ground. Yet we see that from time to time one survives--one perhaps in a million; but how--whether by a quicker growth or a harder or more poisonous thorn, an unpalatable leaf, or some other secret agency--we cannot guess. First as a diminutive scrubby shrub, with numerous iron-hard stems, with few and small leaves but many thorns, it keeps its poor flowerless frustrate life for perhaps half a century or longer, without growing more than a couple of feet high; and then, as by a miracle, it will spring up until its top shoots are out of reach of the browsing sheep, and in the end it becomes a tree with spreading branches and fully developed leaves, and flowers and fruit in their season.