We shall not continue the study further than the beginning of the sixteenth century. It is true that, if we were to refer to several sixteenth-century authors, we should be in possession of a very highly developed and detailed mass of teaching on many points which earlier authors left to some extent obscure. We deliberately refrain nevertheless from doing so, because the whole nature of the sixteenth-century literature was different from that of the fourteenth and fifteenth; the early years of the sixteenth century witnessed the abrogation of the central authority which was a basic condition of the success of the mediæval system; and the same period also witnessed 'radical economic changes, reacting more and more on the scholastic doctrines, which found fewer and fewer defenders in their original form.'[1] [Footnote 1: Cossa, _op. cit._, p. 151. Ashley warns us that 'we must be careful not to interpret the writers of the fifteenth century by the writers of the seventeenth' (_Economic History_, vol. i. pt. ii. p. 387). These later writers sometimes contain historical accounts of controversies in previous centuries, and are relevant on this account.] § 2. _Economic_. It must be clearly understood that the political economy of the mediævals was not a science, like modern political economy, but an art. 'It is a branch of the virtue of prudence; it is half-way between morality, which regulates the conduct of the individual, and politics, which regulates the conduct of the sovereign. It is the morality of the family or of the head of the family, from the point of view of the good administration of the patrimony, just as politics is the morality of the sovereign, from the point of view of the good government of the State. There is as yet no question of economic laws in the sense of historical and descriptive laws; and political economy, not yet existing in the form of a science, is not more than a branch of that great tree which is called ethics, or the art of living well.'[1] 'The doctrine of the canon law,' says Sir William Ashley, 'differed from modern economics in being an art rather than a science. It was a body of rules and prescriptions as to conduct, rather than of conclusions as to fact. All art indeed in this sense rests on science; but the science on which the canonist doctrine rested was theology. Theology, or rather that branch of it which we may call Christian ethics, laid down certain principles of right and wrong in the economic sphere; and it was the work of the canonists to apply them to specific transactions and to pronounce judgment as to their permissibility.'[2] The conception of economic laws, in the modern sense, was quite foreign to the mediæval treatment of the subject. It was only in the middle of the fourteenth century that anything approaching a scientific examination of the phenomena of economic life appeared, and that was only in relation to a particular subject, namely, the doctrine of money.[3]