2.4.38b However, the quality of justice tends to be examined not simply. For, it is asked about the thing (=the action) itself whether it is worth a punishment or reward; or (it is asked) about the degree of the punishment or the reward, which can be blamed as either greater or smaller.
2.4.39 Also, utility (of a law) is decided sometimes by its nature and sometimes by the times. Some (laws) tends to be doubted whether it should be obtained (=enforced) or not. Indeed, one must not ignore the fact that laws tend to be blamed sometimes as a whole and sometimes in part, as an example of both of these is shown to us in the famous orations.
2.4.40 Also, it doesn't deceive me that there are some laws which are not introduced as perpetual ones but (are) about honours or imperia, just as there was Lex Manilia and there is an oration of Cicero's about it. However, nothing about these things can be taught here: for (these things) are consistent not with the common quality (but) with the one peculiar to the things about which it is discussed.
2.4.41 With these (ways) did the old people exercise the ability of speaking, with the method of argument taken from dialectics. For there is an agreement that it was instituted among Greek teachers around the time of Demetrius of Phaleum to discuss matters made for the imitation of the lawcourt and the parliament.
2.4.42 As I've acutually confessed in another book, I verify little whether this kind of exercise (=declamatio) was invented by him; But even those who assert this most strongly are not supported by any sufficiently adequate author. Cicero is the authority (for the fact) that Latin oratory teachers indeed has started (teaching) in the later years of L. Crassus: Plotius was the most distinguished of them.