You need only look around you, replied Philo, to satisfy yourself with regard to this question.  A tree bestows order and organisation on that tree which springs from it, without knowing the order; an animal in the same manner on its offspring; a bird on its nest; and instances of this kind are even more frequent in the world than those of order, which arise from reason and contrivance.  To say, that all this order in animals and vegetables proceeds ultimately from design, is begging the question; nor can that great point be ascertained otherwise than by proving, a priori, both that order is, from its nature, inseparably attached to thought; and that it can never of itself, or from original unknown principles, belong to matter.

But further, DEMEA; this objection which you urge can never be made use of by cleanthes, without renouncing a defence which he has already made against one of my objections.  When I inquired concerning the cause of that supreme reason and intelligence into which he resolves every thing; he told me, that the impossibility of satisfying such inquiries could never be admitted as an objection in any species of philosophy.  “We must stop somewhere”, says he; “nor is it ever within the reach of human capacity to explain ultimate causes, or show the last connections of any objects.  It is sufficient, if any steps, so far as we go, are supported by experience and observation.”  Now, that vegetation and generation, as well as reason, are experienced to be principles of order in nature, is undeniable.  If I rest my system of cosmogony on the former, preferably to the latter, it is at my choice.  The matter seems entirely arbitrary.  And when cleanthes asks me what is the cause of my great vegetative or generative faculty, I am equally entitled to ask him the cause of his great reasoning principle.  These questions we have agreed to forbear on both sides; and it is chiefly his interest on the present occasion to stick to this agreement.  Judging by our limited and imperfect experience, generation has some privileges above reason:  for we see every day the latter arise from the former, never the former from the latter.

Compare, I beseech you, the consequences on both sides.  The world, say I, resembles an animal; therefore it is an animal, therefore it arose from generation.  The steps, I confess, are wide; yet there is some small appearance of analogy in each step.  The world, says cleanthes, resembles a machine; therefore it is a machine, therefore it arose from design.  The steps are here equally wide, and the analogy less striking.  And if he pretends to carry on my hypothesis a step further, and to infer design or reason from the great principle of generation, on which I insist; I may, with better authority, use the same freedom to push further his hypothesis, and infer a divine generation or theogony from his principle of reason.  I have at least some faint shadow of experience, which is the utmost that can ever be attained in the present subject.  Reason, in innumerable instances, is observed to arise from the principle of generation, and never to arise from any other principle.