Now, according to this method of reasoning, Demea, it follows (and is, indeed, tacitly allowed by Cleanthes himself) that order, arrangement, or the adjustment of final causes is not, of itself, any proof of design; but only so far as it has been experienced to proceed from that principle. For ought we can know a priori, matter may contain the source or spring of order originally, within itself, as well as mind does; and there is no more difficulty in conceiving, that the several elements, from an internal unknown cause, may fall into the most exquisite arrangement, than to conceive that their ideas, in the great, universal mind, from a like internal, unknown cause, fall into that arrangement. The equal possibility of both these suppositions is allowed. But by experience we find, (according to Cleanthes) that there is a difference between them. Throw several pieces of steel together, without shape or form ; they will never arrange themselves so as to compose a watch: Stone, and mortar, and wood, without an architect, never erect a house. But the ideas in a human mind, we see, by an unknown, inexplicable economy, arrange themselves so as to form the plan of a watch or house. Experience, therefore, proves, that there is an original principle of order in mind, not in matter. From similar effects we infer similar causes. The adjustment of means to ends is alike in the universe, as in a machine of human contrivance. The causes, therefore, must be resembling.