《Natural History（6 自然史第6卷）》：

　　Some animals， and they are the most mild， innocent， and tranquil， are contented with remaining at a certain distance from us， and living in our fields； others more fierce and distrustful， conceal themselves in the recesses of woods； others， as if they knew there was no safety on the surface of the earth， dig themselves subterraneous abodes， take shelter in caverns， or gain the summits of most inaccessible mountains； and others， the most ferocious and most powerful， inhabit deserts only， and reign like sovereigns in those burning climates， where man， as savage as themselves， is unable to dispute the empire with them.

　　As all beings， even the most independent， are subjected and governed by physical laws， and as brute animals， as well as man， experience the infiuences of the air and soil， so it appears， that the same causes which have softened and civilized the human species in our climates， have produced similar effects upon all other species. The wolf， which is perhaps the most ferocious animal in the temperate zone， is by no means so terrible or cruel as the tiger， the panther， and the lion of the torrid zone； or as the white bear， the lynx， and the hyaena of the frozen zone. And this difference is not only general， as if Nature， to give a degree of harmony to her productions， had calculated the climate for the species， or the species for the climate， but in each particular species the climate is calculated for the manner， and the manners for the climate. In America， where the heat is less violent， and the air and soil more benign than in Africa， though under the same line， the lion， tiger， and panther， have nothing terrible in them but the name. They are no longer tyrants of the forests， intrepid enemies of mankind， monsters which delight in blood and carnage： but they usually run from before man， and instead of waging open war even against other animals， employ stratagem and artifice to take them by surprise； in a word， they may be rendered subservient and almost domestic； therefore were ferocity and cruelty the characteristic of their natures， they must have degenerated， or rather felt the influence of the climate； under a milder sky their dispositions have become milder； every excess in them has been tempered， and by these changes they have become more conformable to the nature of the country which they inhabit.

　　The vegetables which cover this earth and are more connected with it than the animal that feeds upon them， partake in a superior degree of the nature of the climate. Every country， every degree of temperature， has its particular plants. At the foot of the Alps we find those of France and Italy， and on their summit those of the northern regions， which very plants we also meet with on the frozen pinnacles of the African mountains. On the south side of the mountains which separate the Mogul empire from the kingdom of Cashmire， we see all the plants，of the Indies， and on the other side we are surprised to find none but those of Europe. It is from intemperate climates that we also derive drugs， perfumes， poisons and all the plants whose qualities are excessive. The productions of temperate climates， on the contrary are always mild. Of such happy spots， herbs and roots the most wholesome， the sweetest fruits， the gentlest animals and the most polished men， are the delightful appurtenances. Thus the earth produces plants， the earth and plants make animals， and of the earth， plants， and animals， are formed men； for the qualities of vegetables， proceed immediately from the soil and air； the temperament and other relative qualities of animals which feed on herbs， have a close affinity to the particular kinds they use， and the physical qualities of men， and other animals which subsist on flesh， as well as on vegetables， depend， though more remotely， on the same causes， whose infiuence extends even to disposition and manners. Size and form， which appear to be absolute and determined qualities， depend， nevertheless， like the relative qualities upon the influence of the climate. The size of our largest animals are greatly inferior to that of the elephant， thinoceros， or hippopotamus； our largest birds are but small if we compare them with the ostrich， condor， or the cassowary； and what comparison can be made between the fishes， lizards， and serpents of our regions， and the whale， the walrus， and manati， which inhabit the northern seas； or the crocodiles， large lizards， and enormous adders which infest the southern climes， both by land and water?

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