But in all decisions of taste or external beauty, all the relations are beforehand obvious to the eye; and we thence proceed to feel a sentiment of complacency or disgust, according to the nature of the object, and disposition of our organs.
Euclid has fully explained all the qualities of the circle; but has not in any proposition said a word of its beauty.

The reason is evident.

The beauty is not a quality of the circle.

It lies not in any part of the line, whose parts are equally distant from a common centre.

It is only the effect which that figure produces upon the mind, whose peculiar fabric of structure renders it susceptible of such sentiments.