Since we have previously said that one ought to choose that which is intermediate, not the excess nor the defect, and that the intermediate is determined by the dictates of the right rule, let us discuss the nature of these dictates.
Lehenago erdiko terminoa-eta ez gehiegikeria ezta gabezia ere-aukeratu behar dela eta (20) erdiko terminoa arrazoi zuzenak esaten duen hori dela esan dugunez, azter dezagun hori.