For the intention to be right in an action reason needs to be correct and the desire has to be in accordance with right reason. In addition it is necessary to form an ethical habit in order to acquire the actual virtue. Both rational parts of the soul are ordered to truth. Something which is an object of knowledge exists of necessity and is therefore eternal. First principles are acquired by induction.
Art is concerned with bringing something into existence.
To think by art is to investigate how to generate something which may or may not exist. Art is concerned with production, not with action. One doesn't deliberate about things which are unchanging or which are not in one's power to do. Therefore prudence can't be scientific knowledge or an art. Prudence is a disposition with true reason and ability for actions concerning human goods.