According to Herbert Spencer evolution is progress from the simple to the complicated. Let us accept this definition. Have we the right to set up a scale of values and place the complicated above the simple? Is the latter not the more perfect because it has more power of resistance, greater durability, and can hold its own triumphantly against all destructive influences? Is not evolution, then, a retrogression from the perfect, because simple, to the more complicated, and therefore more fragile, more easily upset and less capable of resistance to harm? Is it not sheer egocentrism if we appraise the value of living beings according to their greater or less resemblance to ourselves, and judge them to be less or more worthy in proportion to their disparity with us? Are the fish which, living in the sea wherein we cannot exist, can inhabit the greater part of the globe, are wild duck which fly, swim and walk, not more perfect than we, who have had to conquer the air and the water by artificial means? Is not the mouse's hearing sharper than ours? The eagle's sight keener? The dog's scent incomparably more delicate? Has not the carrier pigeon an infinitely better sense of locality than we have? Are not many beasts physically stronger, more nimble and agile than man? His only claim to superiority rests on the greater perfection of his consciousness. Why do not all living creatures participate equally in the evolution to which this superiority is due? Why does it not take place in every organism and lead the unicellular living being in an unbroken ascent to the level of Goethe or Napoleon, or to a still more lofty one, if such an one exist anywhere in the universe?
If one could believe in a Ruling Power and the plan of the universe as its work, would it not be terribly cruel and revoltingly unjust that this power, instead of treating all living beings alike, should make a kind of selection of grace and lead some up to a higher level while it condemned others to lasting lowliness, and that it should ordain that on the road from the unicellular organism to man, countless connecting links should be left hopelessly behind and not be permitted to continue their ascent? Or must we admit the humiliating conclusion that a greater amount of consciousness does not necessarily imply higher rank and greater dignity, and that a protista, with its almost unimaginably pale and narrow consciousness, can have just as great a feeling of well-being as man with his immeasurably superior intellectual life; that therefore the protista suffers no wrong if it never gets beyond its present stage of evolution; and finally that the amount of the outer world which man can absorb in his consciousness is as far removed from the entirety of the universe as the contents of the protista's consciousness are from that of the human mind? No answer can be found to these questions. Whatever purports to be an answer, be it introduced as theology or as philosophy, is visionary or nonsensical. We must resign ourselves to moving in a very small circle moderately illuminated by Reason, while all around, if we seek to penetrate beyond it, we perceive gruesome darkness.