It may be remember'd that in the introduction, the
reader is desired to consider the surfaces of objects
as so many shells of lines, closely connected together,
which idea of them it will now be proper to call to
mind, for the better comprehending not only this, but
all the following chapters on composition.
The constant use made of lines by mathematicians,
as well as painters, in describing things upon paper, hath
estblish'd a conception of them, as if actually existing
on the real forms themselves. This likewise we suppose,
and shall set out with saying in general -- That the straight
line, and the circular line, together with their different
combinations, and variations, &c. bound, and circum-
scribe all visible objects whatsoever, thereby producing
such endless variety of forms, as lays us under the ne-
cessity of dividing, and distinguishing them into general
classes; leaving the intervening mixtures of appearances
to the reader's own farther observation.
First, ^* objects composed of straight lines only, as the
cube, or of circular lines, as the sphere, or of both, to-
gether, as cylinders and cones, &c.

Secondly,

^* Fig. 23.
T. p. I.

[38]

Secondly, † those composed of straight lines, circular
lines, and of lines partly straight, and partly circular, as
the capitals of columns, and vases, &c.
Thirdly, ‡ those composed of all the former together
with an additions 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, || 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 de-
grees 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 com-
pound 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, be-
comes still more ornamental and pleasing, insomuch
that the hand takes a lively movement in making it
with pen or pencil.
And that the serpentine line, by its waving and wind-
ing at the same time different ways, leads the eye in a

pleasing

pleasing manner along the continuity of its variety, if I
may be allowed the expression; and which by its twist-
ing so many different ways, may be said to inclose (tho'
but a single line) varied contents; and therefore all its
variety cannot be express'd on paper by one continued
line, without the assistance of the imagination, or the
help of a figure; see * where that sort of proportion'd,
winding line, which will hereafter be call'd the precise
serpentine line, or line of grace, is represented by a fine
wire, properly twisted round the elegant and varied
figure of a cone.

* Fig. 26.
T p I.