But insteed of meeting with what I look’d for, I met with somewhat more admirable; and that was, that I found my self utterly unable to see through them when placed both together, though they were transparent enough when asunder; and though I could see through twice the thickness, when both of them were fill’d with the same colour’d liquors, whether both with the Yellow, or both with the Blue, yet when one was fill’d with the Yellow, the other with the Blue, and both looked through, they both appear’d dark, onely when the parts near the tops were look’d through, they exhibited Greens, and those of very great variety, as I expected, but the Purples and other colours, I could not by any means make, whether I endeavour’d to look through them both against the Sun, or whether I plac’d them against the hole of a darkned room.

But notwithstanding this mis-ghessing, I proceeded on with my trial in a dark room, and having two holes near one another, I was able, by placing my Wedges against them, to mix the ting’d Rays that past through them, and fell on a sheet of white Paper held at a convenient distance from them as I pleas’d; so that I could make the Paper appear of what colour I would, by varying the thicknesses of the Wedges, and consequently the tincture of the Rays that past through the two holes, and sometimes also by varying the Paper, that is, insteed of a white Paper, holding a gray, or a black piece of Paper.

Whence I experimentally found what I had before imagin’d, that all the varieties of colours imaginable are produc’d from several degrees of these two colours, namely, Yellow and Blue, or the mixture of them with light and darkness, that is, white and black.  And all those almost infinite varieties which Limners and Painters are able to make by compounding those several colours they lay on their Shels or Palads, are nothing else, but some compositum, made up of some one or more, or all of these four.

Now, whereas it may here again be objected, that neither can the Reds be made out of the Yellows, added together, or laid on in greater or less quantity, nor can the Yellows be made out of the Reds though laid never so thin; and as for the addition of White or Black, they do nothing but either whiten or darken the colours to which they are added, and not at all make them of any other kind of colour:  as for instance, Vermilion, by being temper’d with White Lead, does not at all grow more Yellow, but onely there is made a whiter kind of Red.  Nor does Yellow Oker, though laid never so thick, produce the colour of Vermilion, nor though it be temper’d with Black, does it at all make a Red; nay, though it be temper’d with White, it will not afford a fainter kind of Yellow, such as masticut, but onely a whiten’d Yellow; nor will the Blues be diluted or deepned after the manner I speak of, as Indico will never afford so fine a Blue as Ultramarine or Bise; nor will it, temper’d with Vermilion, ever afford a Green, though each of them be never so much temper’d with white.