Color samples of the seven simple and natural principal colors.
Schäffer's principal colors were red, yellow, blue, white, black, brown, and green, and he includess "members"—the pure colors —of each group. The heraldic imagery of the presentation suggests an extra significance for red, yellow and blue, in the size and placement on the page of those shields.
Source: Farbenmuster der sieben einfachen und natürlichen Hauptfarben. From Jacob Christian Schäffer, Entwurf einer allgemeinen Farbenverein . . . (Regensburg, 1769), plate I.
Credit: Photograph © 2002 Board of Trustees, National Gallery of Art, Washington, D.C.