straining. Besides, it signifies just nothing to the effect produced,
whether a body has its parts connected and makes its impression at once;
or, making but one impression of a point at a time, it causes a
succession of the same or others so quickly as to make them seem united;
as is evident from the common effect of whirling about a lighted torch
or piece of wood: which, if done with celerity, seems a circle of fire.

SECTION X.

UNITY WHY REQUISITE TO VASTNESS.

It may be objected to this theory, that the eye generally receives an
equal number of rays at all times, and that therefore a great object
cannot affect it by the number of rays, more than that variety of
objects which the eye must always discern whilst it remains open. But to
this I answer, that admitting an equal number of rays, or an equal
quantity of luminous particles to strike the eye at all times, yet if
these rays frequently vary their nature, now to blue, now to red, and so
on, or their manner of termination, as to a number of petty squares,
triangles, or the like, at every change, whether of color or shape, the
organ has a sort of relaxation or rest; but this relaxation and labor so
often interrupted, is by no means productive of ease; neither has it the
effect of vigorous and uniform labor. Whoever has remarked the different
effects of some strong exercise, and some little piddling action, will
understand why a teasing, fretful employment, which at once wearies and
weakens the body, should have nothing great; these sorts of impulses,
which are rather teasing than painful, by continually and suddenly
altering their tenor and direction, prevent that full tension, that
species of uniform labor, which is allied to strong pain, and causes the
sublime. The sum total of things of various kinds, though it should
equal the number of the uniform parts composing some _one_ entire
object, is not equal in its effect upon the organs of our bodies.
Besides the one already assigned, there is another very strong reason
for the difference. The mind in reality hardly ever can attend
diligently to more than one thing at a time; if this thing be little,
the effect is little, and a number of other little objects cannot engage
the attention; the mind is bounded by the bounds of the object; and what
is not attended to, and what does not exist, are much the same in the
effect; but the eye or the mind, (for in this case there is no
difference,) in great, uniform objec