is not to be extended. For them the rule is: "What has been accepted contra rationem juris, is not to be drawn out (producendum) to its consequences,"[1] or again: "What was introduced not by principle, but at first through error, does not obtain in like cases."[2]
These are true principles making for the consistent development of a body of law. Observe the scope and penetration of some other general rules: "Nuptias non concubitus, sed consensus facit."[3] This goes to the legal root of the whole conception of matrimony, and is still the recognized starting-point of all law upon that subject. Again: "An agreement to perform what is impossible will not sustain a suit."[4] This is still everywhere a fundamental principle of the law of contracts. Again: "No one can transfer to another a greater right than he would have himself,"[5] another principle of fundamental validity, but, of course, like all rules of law subject in its application to the qualifying operation of other legal rules.
Roman jurisprudence recognized the danger of definition: "Omnis definitio in jure civili periculosa est."[6] Yet it could formulate admirable ones; for example: "Inheritance is succession to the sum total (universum jus) of the rights of the deceased."[7] This definition excels in the completeness of its legal view of the matter, and is not injured by the obvious omission to exclude those personal privileges and rights of the deceased which terminate upon his death. Thus we note the sources and constructive principles of the Roman law. We observe that while certain of the former might be called "statutory," the chief means and method of development was the declarative edict of the praetor and the trained labour of the jurisconsults. In these appears the consummate genius of Roman jurisprudence, a jurisprudence matchless in its rational conception of principles of justice which were rooted in a philosophic consideration of human life; matchless also in its carrying through of such principles into the body of the law and the decision of every case.
