5. The demonstrated conclusion not without doubt, precedent to the demonstration.
Another difference between
intuitive and demonstrative knowledge is, that, though in the latter all doubt be removed when, by the intervention
of the intermediate ideas, the agreement or disagreement is perceived, yet before the demonstration there was a
doubt; which in intuitive knowledge cannot happen to the mind that has its faculty of perception left to a degree
capable of distinct ideas; no more than it can be a doubt to the eye (that can distinctly see white and black),
Whether this ink and this paper be all of a colour. If there be sight in the eyes, it will, at first glimpse, without
hesitation, perceive the words printed on this paper different from the colour of the paper: and so if the mind have
the faculty of distinct perception, it will perceive the agreement or disagreement of those ideas that produce
intuitive knowledge. If the eyes have lost the faculty of seeing, or the mind of perceiving, we in vain inquire after
the quickness of sight in one, or clearness of perception in the other.