But although no determinate limit presents itself. to the increase of food, and to a population commensurate with it, other than the limited productiveness of the earth itself, we can scarcely be warranted in supposing that all the productive powers of its surface can be made subservient to the use of man, in exclusion of all the plants and animals not entering into his stock of subsistence; that all the elements and combinations of elements in the earth, the atmosphere, and the water, which now support such various and such numerous descriptions of created beings, animate and inanimate, could be withdrawn from that general destination, and appropriated to the exclusive support and increase of the human part of the creation; so that the whole habitable earth should be as full of people as the spots most crowded now are or might be made, and as destitute as those spots of the plants and animals not used by man.
The supposition cannot well be reconciled with that symmetry in the face of nature, which derives new beauty from every insight that can be gained into it.
A nice description of ecosystem services, as well as a statement of value.
According to the link, the speech caught on at the time but was gradually forgotten. Maybe some version of the idea went on to influence Thoreau and the incubating environmental movement.