John Muir, The Story of My Boyhood and Youth
(Boston: Houghton Mifflin Company, 1916), pp. 356-357:
Why should man value himself as more than a small part of the one great unit of creation? And what creature of all that the Lord has taken the pains to make is not essential to the completeness of that unit the cosmos? The universe would be incomplete without man; but it would also be incomplete without the smallest transmicroscopic creature that dwells beyond our conceitful eyes and knowledge.
From the dust of the earth, from the common elementary fund, the Creator has made Homo sapiens. From the same material he has made every other creature, however noxious and insignificant to us. They are earthborn companions and our fellow mortals. The fearfully good, the orthodox, of this laborious patchwork of modern civilization cry "Heresy" on every one whose sympathies reach a single hair's breadth beyond the boundary epidermis of our own species. Not content with taking all of earth, they also claim the celestial country as the only ones who possess the kind of souls for which that imponderable empire was planned.
Henry David Thoreau, Journals
(April 2, 1852):
It appears to me that, to one standing on the heights of philosophy, mankind and the works of man will have sunk out of sight altogether; that man is altogether too much insisted on. The poet says the proper study of mankind is man. I say, study to forget all that; take wider views of the universe. That is the egotism of the race.