Let it not then be said, that it is degrading man to reduce his functions to a pure mechanism; that it is shameful to undervalue him, scandalously to abuse him, to compare him to a tree; to an abject vegetation. The philosopher devoid of prejudice does not understand this language, invented by those who are ignorant of what constitutes the true dignity of man.
A tree is an object, which in its station, joins the useful with the agreeable; it merits our approbation when it produces sweet and pleasant fruit; when it affords a favourable shade. All machines are precious, when they are truly useful, when they faithfully perform the functions for which they are designed.
Yes, I speak it with courage, reiterate it with pleasure, the honest man, when he has talents, when he possesses virtue, is, for the beings of his species, a tree that furnishes them with delicious fruit, that affords them refreshing shelter: the honest man is a machine of which the springs are adapted to fulfil its functions in a manner that must gratify the expectation of all his fellows. No, I should not blush. I should not feel degraded, to be a machine of this sort; and my heart would leap with joy, if I could foresee that the fruit of my reflections would one day be useful to my race, consoling to my fellow man.
System of Nature by d’Holdbach