13. Colours indefinable to the born-blind.
He that should use the word rainbow to one who knew all those colours,
but yet had never seen that phenomenon, would, by enumerating the figure, largeness, position, and order of the
colours, so well define that word that it might be perfectly understood. But yet that definition, how exact and
perfect soever, would never make a blind man understand it; because several of the simple ideas that make that
complex one, being such as he never received by sensation and experience, no words are able to excite them in his
mind.