257.23-260.4 In which is explained the correspondence that natural mobiles have with the weights of a balance.
Thus we will first examine the things that happen in the scale pan, so that we may then show that all these things happen in the case of natural mobiles.
Thus let line ab be understood to be an equal-armed balance, whose center, above which motion takes place, is c, precisely dividing line ab in two; and let two weights, e and o, be suspended from points a and b. Accordingly in the case of weight e three things can happen: either it is at rest, or it is moved upward, or it is moved downward. Consequently if weight e is heavier