(latter) would perhaps have been very difficult for him to make an
Intelligible mention of, because those Minute disparities having not been
taken notice of by men for want of touch as Exquisite as our Blind Mans,
are things he could not have Intelligibly express'd, which will easily seem
Probable, if you consider, that under the name of Sharp, and Sweet, and
Sour, there are abundance of, as it were, immediate peculiar Relishes or
Tasts in differing sorts of Wine, which though Critical and Experienc'd
Palats can easily discern themselves cannot make them be understood by
others, such Minute differences not having hitherto any Distinct names
assign'd them. And it seems that there was somthing in the Forms of
Asperity that was requisite to the Distinction of Colours, besides the
Degree of it, since he found it so difficult to distingush Black and White
from one another, though not from other Colours. For I might urge, that he
seems not consonant to himself about the _Red_, which as you have seen in
one place, he represents as somewhat more Asperous than the _Blew_; and in
another, very Smooth: But because he speaks of this Smoothness in that
place, where he mentions the Roughness of _Black_, we may favourably
presume that he might mean but a _comparative Smoothness_; and therefore I
shall not Insist on this, but rather Countenance my Conjecture by this,
that he found it so Difficult, not only, to Discriminate Red and Blew,
(though the first of our promiscuous Experiments will inform you, that the
Red reflects by great Odds more Light than the other) but also to
distinguish Black and White from one another, though not from other
Colours. And indeed, though in the Ribbonds that were offer'd him, they
might be almost equally Rough, yet in such slender Corpuscles as those of
Colour, there may easily enough be Conceiv'd, not only a greater Closeness
of Parts, or else Paucity of Protuberant Corpuscles, and the little extant
Particles may be otherwise Figur'd, and Rang'd in the White than in the
Black, but the Cavities may be much Deeper in the one than the other.