398 ON THE STRUCTURE AND HABITS 



properties, requires to be studied in this manner before we can obtain a correct 

 knowledge of its Nature. These two conditions of an object are constantly 

 considered in Natural History. As an instance, let us take a plant : I may 

 know its colour, size, form, weight, and the place in which it grows, but unless 

 I know the changes which are undergone by the plant with regard to its size, 

 form, weight, colour, and so on, I cannot be said to know its natural history. 



Although these remarks will extend to but a small portion of the objects of 

 Natural History, yet a few observations on the relation they bear to other objects 

 in Nature will not be unnecessary. 



All objects in Nature are arranged in three great divisions, which may be 

 respectively represented by a mineral, a plant, and an animal ; and the collections 

 of objects in Nature bearing the characters of these things are called the mineral, 

 vegetable, and animal kingdoms. Now the basis of every thing in Nature is 

 matter, and the only difference between a stone and a plant is, that the latter 

 form of matter is endowed with properties the former does not possess. Whilst 

 the matter, again, of which an animal is constituted differs from the matter of 

 the plant, in being endowed with properties denied to the plant. The Mineral 

 Kingdom, then, the lowest of these divisions, is universally subject to what are 

 called the laws of matter, or physical laws, but when we ascend to the Vegetable 

 Kingdom we shall find a new property added to matter, which to a great extent 

 controls and modifies the mere physical laws to which minerals are subject ; this 

 is the principle of vitality. On ascending higher, and entering the Animal King- 

 dom, we find other properties added . to matter which exercise a controlling 

 influence over the properties it possesses as a mineral or a plant. The laws which 

 minerals obey in common with plants and animals are called physical laws ; the 

 laws which the principles of vitality in plants obey, and which they have in 

 common with animals, are called the laws of organie life, or organic laws ; whilst 

 the laws which the animal machine obeys, distinguished from the two others, are 

 called the laws of animal life. Each of these departments comprehends an almost 

 countless number of objects, and the attention of scientific men has been directed 

 at all times to the means of distinguishing these from each other. Hence have 

 resulted those systems of classification, the permanence of which being secured 

 by the art of printing, have been gradually improving up to the present day. In 

 this manner upwards of 80,000 plants have been described, so that a botanist 

 can easily distinguish one from another. In the Animal .Kingdom, 20,000 

 species of insects alone have been described as indigenous to Britain. Our know- 

 ledge of the objects of Nature is thus every day increasing, and we are furnished 

 with the means of deducing those great principles or laws by which the Deity 

 upholds all things, and by a knowledge of which Man can alone expect to ensure 



