[21] We must now examine what is symbolized by the Cherubim and the sword of flame which turns every way. I suggest that they are an allegorical figure of the revolution of the whole heaven. For the movements assigned to the heavenly spheres are of two opposite kinds, in the one case an unvarying course, embodying the principle of sameness, to the right, in the other a variable course, embodying the principle of otherness, to the left.
[22] The outermost sphere, which contains what are called the fixed stars, is a single one and always makes the same revolution from east to west. But the inner spheres, seven in number, contain the planets and each has two motions of opposite nature, one voluntary, the other under a compelling force. Their involuntary motion is similar to that of the fixed stars, for we see them pass every day from east to west, but their own proper motion is from west to east, and it is in this that we find the revolutions of the seven governed also by certain lengths of time. These lengths are the same in the case of three whose course is equal, and these three which have the same rate of speed are known as the Sun, the Morning-star, and the Sparkler (or Mercury). The others have unequal courses and different lengths of time in revolution, though these too preserve a definite proportion to each other and the above-named three.
[23] One of the Cherubim then symbolizes the outermost sphere of the fixed stars. It is the final heaven of all, the vault in which the choir of those who wander not move in a truly divine unchanging rhythm, never leaving the post which the Father who begat them has appointed them in the universe. The other of the Cherubim is the inner contained sphere, which through a sixfold division He has made into seven zones of regular proportion and fitted each planet into one of them.
[24] He has set each star in its proper zone as a driver in a chariot, and yet He has in no case trusted the reins to the driver, fearing that their rule might be one of discord, but He has made them all dependent on Himself, holding that thus would their march be orderly and harmonious. For when God is with us all we do is worthy of praise; all that is done without Him merits blame.