For that which can foresee by the exercise of mind is by nature ​intended to be lord and master, and that which can with its body give effect to ​such foresight is a subject, and by nature slave; hence master and slave have ​the same interest. Now nature has distinguished between the female and the ​slave. For she is not stingy, like the smith who fashions the Delphian knife for ​many uses; she makes each thing for a single use, and every instrument is best ​made when intended for one and not for many uses.