Secondly, [Fig. 24 T p. I] those composed of straight lines, circular lines, and of lines partly straight, and partly circular, as the capitals of columns, and vases, &c.
Thirdly, [Fig. 25 T p. I] those composed of all the former together with an addition of the waving line, which is a line more productive of beauty than any of the former, as in flowers, and other forms of the ornamental kind: for which reason we shall call it the line of beauty.
Fourthly, [Fig. 26 T p. I] those composed of all the former together with the serpentine line, as the human form, which line hath the power of super-adding grace to beauty. Note, forms of most grace have least of the straight line in them.
It is to be observed, that straight lines vary only in length, and therefore are least ornamental.
That curved lines as they can be varied in their degrees of curvature as well as in their lengths, begin on that account to be ornamental.
That straight and curv'd lines join'd, being a compound line, vary more than curves alone, and so become somewhat more ornamental.
That the waving line, or line of beauty, varying still more, being composed of two curves contrasted, becomes still more ornamental and pleasing, insomuch that the hand takes a lively movement in making it with pen or pencil.