Now take up a natural object, it does not matter what, and you are studying one of a group, a member of a series; whatever knowledge you get about it is so much towards the science which includes all of its kind. Break off an elder twig in the spring; you notice a ring of wood round a center of pith, and there you have at a glance a distinguishing character of a great division of the vegetable world. You pick up a pebble. Its edges are perfectly smooth and rounded: why? you ask. It is water-worn, weather-worn. And that little pebble brings you face to face with disintegration, the force to which, more than to any other, we owe the aspects of the world which we call picturesque – glen, ravine, valley, hill. It is not necessary that the child should be told anything about disintegration or dicotyledon, only that he should observe the wood and pith in the hazel twig, the pleasant roundness of the pebble; by-and-by he will learn the bearing of the facts with which he is already familiar – a very different thing from learning the reason why of facts which have never come under his notice.