"State the opinion of the ancient astronomers as to how the planets move. The ancients, Eudoxus and , and their follower Ptolemy did not advance beyond circles... for in Book XIII of the ', Chapter 2, Ptolemy writes as follows:"But let no one judge that these interweavings of circles which we postulate are difficult, on the ground that... manual imitation of these interweavings is... intricate. For it is not right for our human things to be compared on a basis of equality with the immortal gods, and for us to seek the evidence for very lofty things from examples of very unlike things. ...Indeed we must try hard to fit the most simple hypotheses to the celestial movements... but if that is not successful, whatever sort of hypotheses can be used. ...[W]e should not judge what is simple in celestial bodies by the examples of things which seem to us to be simple ...For ...he who wishes to judge celestial things in this way will not recognize as simple any of those movements which take place in the heavens, not even the invariable constancy of the first movement: because it is ...impossible to find among men this thing (namely, something which stays in the same state perpetually). Therefore we must not form our judgement upon terrestrial things, but upon the natures of the things which are in the heavens and upon the unchanging steadfastness of their movements. So... in this way all the movements are seen to be simple, and much more simple than those movements which seem to us to be simple. For we are unable to suspect them of any labor or any difficulty in their revolutions." So [says] Ptolemy."