5. Rainbow to be viewed as a new creature and as God's sign-board 65. 6. Colors of the rainbow. a. What are they and their number 66. b. What do they signify 67. 7. To what end should the rainbow serve us 68. C. THE RAINBOW. 56. They further dispute whether the natural causes in the rainbow signify this. It is well known that philosophers, especially Aristotle in his book on Meteors, use all sorts of arguments on the color of the rainbow, on the character of the clouds where it is produced, and on its curvature. Quite appropriately the resemblance is noted between a mirror, which reflects an image, and the moist and arched cloud, which catches the rays of the sun, and by reflection produces the rainbow. Reason sees in such phenomena what appears to it most probable, but it does not discover the truth everywhere. That is not in the power of the creature but of the Creator alone. As for me, I have never given to any book less credence than to that on meteors, the basic principle of which is the assumption that natural causes explain everything. 57. Some declare the rainbow to be a forerunner of a storm lasting three days, which I am ready to admit, but this much is certain, that it signifies that there will never be another flood. However, it derives this signification, not from any natural causes but only from the Word of God. Its meaning is such, only because God orders and declares it to be so through his Word. Circumcision was a token that the seed of Abraham were the people of God; yet circumcision did not have this meaning in itself, but only through the Word which was joined with it. Again, the clothing of skin signified life and safety, not because they contained this guarantee by nature, but because God had promised it. So, the significance of the rainbow that the flood shall not return, is not based upon the Word of God. 58. I do not altogether ignore theories along the lines of natural law concerning these matters; but since they are not substantiated, I place little trust in them. The reasoning of Aristotle regarding the humid and hollow cloud as the cause of the rainbow is not reliable, such clouds may exist without producing a rainbow. Again, according to the greater or lesser density of the medium, the bow may appear wider or narrower. I have seen here at Wittenberg a circular rainbow, forming a complete ring, not simply an arch terminating on the surface of the earth, as rainbows generally appear. Why, then, do rainbows assume different forms at different times? A philosopher, I suppose, will think of some reason; for he will consider it a disgrace not to be able to assign a reason for all things. But indeed, he will never persuade me to believe that he speaks the truth.