On this subject Emerson and Lewis Mumford are in agreement. Mumford, writing much later, does a better job of it. I have broken up two long paragraphs from his The Condition of Man. on page 7, to make them more digestible online.
Man’s life differs from that of most other organizations in that individuation has become more important to him than strict conformity to type: he participates in all the characters of his species, and yet, by the very complexity of his needs, each individual makes over the life-course of the species and achieves a character and becomes a person.
The more fully he organizes his environment, the more skillfully he associates in groups, the more constantly he draws from his social heritage, the more does the person emerge from society as its fulfillment and perfection. But that process is never finished. Like the measuring worm at the end of a twig, in Albert Pinkham Ryder’s illustration, Every other animal but man is a complete representation of his species: man remains the unfinished animal, ever reaching out into the unknown.
Man’s growth, therefore, is not completed by his biological fulfillment as a mate and a parent; nor is it completed by his death. Man’s nature is a self-surpassing and a self-transcending one: his utmost achievements are always the beginnings and his fullest growth must still leave him unsatisfied.
This quality of self-transcendence must be joined to another fact about the nature of man: namely, that his instinctive and automatic activity lies a whole stratum where purpose and meaning have full play.
A meaningless life and a purposeless life belong to the not-yet-human. Man does not, therefore, merely function towards survival, his own or that of his species, like other animals: he functions towards ends, which he himself becomes progressively conscious of and progressively able to define.
Outside such meanings and ends, the bitter words of the Preacher will hold: All is vanity.
Here Mumford is waxing poetic, as Emerson the Transcendentalist, did. Any many others before and since.