the same time current opinion seems to have been so fully formed in accordance with it that a brief enumeration of the doctrine of a just price will serve to set the practice of the day in clearer light. In regard to other matters, it is difficult to determine how far public opinion was swayed by practical experience, and how far it was really moulded by Christian teaching--this is the case in regard to usury. But there can be little doubt about the doctrine of price--which really underlies a great deal of commercial and gild regulations, and is constantly implied in the early legislation on mercantile affairs.'[4] The same author expresses the same opinion in another work: 'The Christian doctrine of price, and Christian condemnation of gain at the expense of another man, affected all the mediæval organisation of municipal life and regulation of inter-municipal commerce, and introduced marked contrasts to the conditions of business in ancient cities. The Christian appreciation of the duty of work rendered the lot of the mediæval villain a very different thing from that of the slave of the ancient empire. The responsibility of proprietors, like the responsibility of prices, was so far insisted on as to place substantial checks on tyranny of every kind. For these principles were not mere pious opinions, but effective maxims in practical life. Owing to the circumstances in which the vestiges of Roman civilisation were locally maintained, and the foundations of the new society were laid, there was ample opportunity for Christian teaching and example to have a marked influence on its development.'[5] In Dr. Cunningham's book entitled _Politics and Economics_ the same opinion is expressed:[6] 'Religious and industrial life were closely interconnected, and there were countless points at which the principles of divine law must have been brought to bear on the transaction of business, altogether apart from any formal tribunal. Nor must we forget the opportunities which directors had for influencing the conduct of penitents.... Partly through the operation of the royal power, partly through the decisions of ecclesiastical authorities, but more generally through the influence of a Christian public opinion which had been gradually created, the whole industrial organism took its shape, and the acknowledged economic principles were framed.' We have quoted these passages from Dr. Cunningham's works at length because they are of great value in helping us to estimate the rival parts played by theory and practice in mediæval economic teaching; in the first place, because the author was by no means prepossessed in favour of the teaching of the canonists, but rather unsympathetic to it; in the second place, because, although his work was concerned primarily with practice, he found himself obliged to make a study of theory before he could properly understand the practice; and lastly, because they point particularly to the effect of the teaching on just price.