When feveral different parts contribute to one effect; or, which is the fame thing, when an effect is produced by the joint action of different inftruments; the fitnefs of fuch parts or inftruments to one another, for the purpofe of producing, by their united action, the effect, is what I call relation: and whereever this is obferved in the works of nature or of man, it appears to me to carry along with it decifive evidence of underftanding, intention, art. In examining, for inftance, the feveral parts of a watch, the fpring, the barrel, the chain, the fufee, the balance, the wheels of various fizes, forms, and pofitions, what is it which would take an obferver's attention, as moft plainly evincing a conftruction, directed by thought, deliberation, and contrivance? It is the fuitablenefs of thefe parts to one another, firft, in the fucceffion and order in which they act; and, fecondly, with a view to the effect finally produced. Thus, referring the fpring to the wheels, our obferver fees in it, that which originates and upholds their motion; in the chain, that which tranfmits the motion to the fufee; in the fufee, that which communicates it to the wheels; in the conical figure of the fufee, if he refer back again to the fpring, he fees that which corrects the inequality of its force.