6 Roscoe Pound 



worthy that, as he puts them, they have something of the idea 

 of authority and command, appropriate to the period just past, 

 and something of the idea of reason and justice, appropriate to 

 the immediate future. 1 



Passing to the classical jurists, in the golden age of juristic 

 law-making, we find the idea of authority and command has dis- 

 appeared, and reason and justice, to which the jurists of the time 

 were striving to make the actual rules of law conform, alone are 

 insisted upon. Thus Celsus (beginning of the second century) 

 and Ulpian, following him, define law (ius) as the "art of what 

 is right and equitable," 2 and the latter defines jurisprudence as 

 "the science of the just and the unjust." 3 Paulus in like manner 

 says law (ius) is "that which is always equitable and right." 4 

 By the middle of the third century, however, the period of the 

 classical jurists is past. Rescripts of the emperor supplant 

 rcsponsa of the jurisconsults as the source of private law, and 

 by the end of the fourth century these rescripts cease to be au- 

 thoritative except for those to whom addressed. From the time 

 of Diocletian (284), imperial legislation becomes the growing- 

 point of the law. This period has Jeft no juridical or philo- 

 sophical treatise to set forth the current notion of law. But it 

 can hardly be an accident that the word lex began to mean law 

 in general during the period of legislation and codification from 

 Diocletian to Justinian. 5 An antiquarian revival in the reign 

 of Justinian preserved for us the formulas of the classical jurists. 

 But the Institutes and Digest give us the legal speculation of the 



1<( Law {lex) is the right reason of commanding and prohibiting." De 

 Legibus, I, 5. "A just sanction, commanding what is upright and prohibit- 

 ing the contrary." Philipp., XI, 12. 



2 Ars aequi et boni, Dig., I, 1, 1, sec. 1. 



3 Dig., I, 1, 10, sec. 2. 



4 Dig., I, 1, 11, pr. 



6 Savigny, Geschichte des Romischen Rechts im Mi/telalter, I, sec. 37. The 

 first case of its use in this sense is in the Lex Dei sine Mosaicorum et 

 Ronianonan Legum Collatio, dating from the end of the fourtli century. 

 In this connection it is of interest to note that while Recht, droit, diritto, all 

 meaning etymologically that which is straight or right, are equivalents of ius 

 and are generic terms, and Gesetz, loi, and legge, equivalents of lex, are 

 properly employed to mean enactment, legislation, or rule, yet loi and legge, 

 for the same reasons that led to the wider meaning of lex, are sometimes 

 used for law in the wider sense. 



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