[PAULUS libro sexto decimo ad Plautium. ] §50.17.1.prRegula est, quae rem quae est breuiter enarrat.
[PAULUS in his sixteenth book on Plautius.] A rule is that which briefly narrates a matter as it is.
non ex regula ius sumatur, sed ex iure quod est regula fiat.
Law is not to be taken from a rule, but a rule is to be made from the law that exists.
per regulam igitur breuis rerum narratio traditur, et, ut ait Sabinus, quasi causae coniectio est, quae simul cum in aliquo uitiata est, perdit officium suum.
Therefore, through a rule a brief narration of matters is handed down, and, as Sabinus says, it is as it were a summary of a case, which, as soon as it is corrupted in any point, loses its function.