[7] Hamerton's _Landscape_. [8] Shelley. [9] Howitt's _Book of the Seasons_. [10] Seneca, _De Beneficiis_. CHAPTER II ON ANIMAL LIFE If thy heart be right, then will every creature be to thee a mirror of life, and a book of holy doctrine. THOMAS A KEMPIS. CHAPTER II ON ANIMAL LIFE There is no species of animal or plant which would not well repay, I will not say merely the study of a day, but even the devotion of a lifetime. Their form and structure, development and habits, geographical distribution, relation to other living beings, and past history, constitute an inexhaustible study. When we consider how much we owe to the Dog, Man's faithful friend, to the noble Horse, the patient Ox, the Cow, the Sheep, and our other domestic animals, we cannot be too grateful to them; and if we cannot, like some ancient nations, actually worship them, we have perhaps fallen into the other extreme, underrate the sacredness of animal life, and treat them too much like mere machines. Some species, however, are no doubt more interesting than others, especially perhaps those which live together in true communities, and which offer so many traits--some sad, some comical, and all interesting,--which reproduce more or less closely the circumstances of our own life. The modes of animal life are almost infinitely diversified; some live on land, some in water; of those which are aquatic some dwell in rivers, some in lakes or pools, some on the sea-shore, others in the depths of the ocean. Some burrow in the ground, some find their home in the air. Some live in the Arctic regions, some in the burning deserts; one little beetle (Hydrobius) in the thermal waters of Hammam-Meskoutin, at a temperature of 130 deg.. As to food, some are carnivorous and wage open war; some, more insidious, attack their victims from within; others feed on vegetable food, on leaves or wood, on seeds or fruits; in fact, there is scarcely an animal or vegetable substance which is not the special and favourite food of one or more species. Hence to adapt them to these various requirements we find the utmost differences of form and size and structure. Even the same individual often goes through great changes. GROWTH AND METAMORPHOSES