But surely beauty is no idea belonging to mensuration; nor has it anything to do with calculation and geometry.

If it had, we might then point out some certain measures which we could demonstrate to be beautiful, either as simply considered, or as related to others; and we could call in those natural objects, for whose beauty we have no voucher but the sense, to this happy standard, and confirm the voice of our passions by the determination of our reason.

But since we have not this help, let us see whether proportion can in any sense be considered as the cause of beauty, as hath been so generally, and, by some, so confidently affirmed.

If proportion be one of the constituents of beauty, it must derive that power either from some natural properties inherent in certain measures, which operate mechanically; from the operation of custom; or from the fitness which some measures have to answer some particular ends of conveniency.

Our business therefore is to inquire, whether the parts of those objects, which are found beautiful in the vegetable or animal kingdoms, are constantly so formed according to such certain measures, as may serve to satisfy us that their beauty results from those measures, on the principle of a natural mechanical cause; or from custom; or, in fine, from their fitness for any determinate purposes.