When not protected by law, by popular favor or superstition, or by other special circumstances, [birds] yield very readily to the influences of civilization, and, though the first operations of the settler are favorable to the increase of many species, the great extension of rural and of mechanical industry is, in a variety of ways, destructive even to tribes not directly warred upon by man.

Man is everywhere a disturbing agent. Wherever he plants his foot, the harmonies of nature are turned to discords.

The improvement of forest trees is the work of centuries. So much more the reason for beginning now.

Man has too long forgotten that the earth was given to him for usufruct alone, not for consumption, still less for profligate waste.

The equation of animal and vegetable life is too complicated a problem for human intelligence to solve, and we can never know how wide a circle of disturbance we produce in the harmonies of nature when we throw the smallest pebble into the ocean of organic life.

Sight is a faculty; seeing is an art.

All Nature is linked together by invisible bonds and every organic creature, however low, however feeble, however dependent, is necessary to the well-being of some other among the myriad forms of life.