y senses: but in my waking
hours, if the sweetness occurs to my imagination, the stimulus of the table
to my hand, or of the window to my eye, prevents the other ideas of the
hardness and whiteness of the sugar from succeeding; and hence I perceive
the fallacy, and disbelieve the existence of objects correspondent to those
ideas, whose tribes or trains are broken by the stimulus of other objects.
And further in our waking hours, we frequently exert our volition in
comparing present appearances with such, as we have usually observed; and
thus correct the errors of one sense by our general knowledge of nature by
intuitive analogy. See Sect. XVII. 3. 7. Whereas in dreams the power of
volition is suspended, we can recollect and compare our present ideas with
none of our acquired knowledge, and are hence incapable of observing any
absurdities in them.

By this criterion we distinguish our waking from our sleeping hours, we can
voluntarily recollect our sleeping ideas, when we are awake, and compare
them with our waking ones; but we cannot in our sleep _voluntarily_
recollect our waking ideas at all.

8. The vast variety of scenery, novelty of combination, and distinctness of
imagery, are other curious circumstances of our sleeping imaginations. The
variety of scenery seems to arise from the superior activity and excellence
of our sense of vision; which in an instant unfolds to the mind extensive
fields of pleasurable ideas; while the other senses collect their objects
slowly, and with little combination; add to this, that the ideas, which
this organ presents us with, are more frequently connected with our
sensation than those of any other.

9. The great novelty of combination is owing to another circumstance; the
trains of ideas, which are carried on in our waking thoughts, are in our
dreams dissevered in a thousand places by the suspension of volition, and
the absence of irritative ideas, and are hence perpetually falling into new
catenations. As explained in Sect. XVII. 1. 9. For the power of volition is
perpetually exerted during our waking hours in comparing our passing trains
of ideas with our acquired knowledge of nature, and thus forms many
intermediate links in their catenation. And the irritative ideas excited by
the stimulus of the objects, with which we are surrounded, are every moment
intruded upon us, and form other links of our unceasing catenations of
ideas.

10. The absence of the stimuli of external bodie