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,