Every percept is such a starting-point; it is an immediate certainty, remaining with us unmodified as the basis 1 Deontology, p. 42.
The reality of the external object is a necessary condition, to exclude hallucinations of the senses; the exact correspondence between the external object and the internal percept is also necessary, but naturally hard to secure, for how can we compare the two?
On the other hand, Hume is certainly right in holding that the distinctive character of a percept as compared with an image is in all ordinary cases the force and liveliness with which it strikes the mind - the distinction, therefore, being one of quality, not of degree.
First he breaks up the percept.
Sense alone will never create orderly experience, as empiricism supposed; but a group of sensations reacted on by thought does so; it becomes, it is, a percept.