 At DEM, which has an angle of 42º, the red of the primary rainbow appears, and below it, at slightly smaller angles, appear the remaining colors of the primary rainbow (orange, yellow, green, blue, violet). At KEM, which has an angle of about 52º, the fainter red of the secondary rainbow appears, and above it, at slightly larger angles, appear the remaining colors of the secondary rainbow (orange, yellow, green, blue, violet). The neighborhood of the two principal angles DEM and KEM alone receive a sufficient number of rays to produce all the colors of the primary and secondary rainbows. Beyond them, there lies only “shadow”, i.e., light rays that, due to their small number, produce no color. The conditions under which colors are produced in the prism do indeed faithfully reproduce those in which the colors of the rainbow are naturally produced, and together the flask, the prism, and Descartes’ physics of light deduce all of the effects of the rainbow.