Study for The Investigation of the Rainbow, Plate 66, Physica Sacra

A gentleman with a dog is surrounded by a small circular rainbow and faces a mountain with a cascading waterfall. The picture contains two large diagrams - the upper portion of the picture consists of two circles and diagonal lines, and the lower portion contains two arches and diagonal lines. The letters P and O appear in the upper portion, while Fig. 1 and the letters S and O appear below. The diagonal lines leading to the arches in the bottom portion are emanating from an eye that appears on the ground, just to the right of the man and his dog.