Nor was it altogether remote from the actual life of the day. Even to the laity of the Middle Ages, war was not a mere conflict of powers, in which the strongest power must necessarily prevail. It was a conflict of rights before a watching God of battles, in which the greatest right could be trusted to emerge victorious. War between States was analogous to the ordeal of battle between individuals: it was a legal way of testing rights. Now ordeal by battle was a mode of procedure in courts of law, and a mode of procedure whose conduct and control belonged to the clergy. If, therefore, war between States is analogous to ordeal, it follows, first, that it is a legal procedure which needs a high court for its interpretation (and what court could be more competent than the papal curia?), and, next, that it is a matter which in its nature touches the clergy. Such ideas were a natural basis for the Church's attempt to control the issues of war and peace; and if we remember these ideas, we shall acquit the Church of any impracticable quixotism. The attempt to control trade and commerce was no less lofty and no less arduous. It is perhaps still easier to stop war than to stop competition; and yet the Church made the attempt. The Christian law of love was set against the economic law of demand and supply. It was canonical doctrine that the buyer should take no more, and the seller offer no less, than the just price of a commodity--a price which would in practice depend on the cost of production. The rule for prices was also the rule for wages: the just wage was the natural complement of the just price. The prohibition of usury and of the taking of interest was another factor in the same circle of ideas. If prices and wages are both to be returns for work done, and returns of an exact equivalence, then, on the assumptions which the canonists made--that the usurer does no work, and that his loan is unproductive of any new value--it necessarily follows that no return is due, or can be justly paid, for the use of borrowed money. Work is the one title of all acquisition, and all acquisition should be in exact proportion to the amount of work done. This is the basic principle, and it is the principle of the Divine Law: _In sudore frontis tuae comedes panem tuum_. Once more, therefore, and once more in an unpromising and intractable material, we find the Church seeking to enforce the unity of the Christian principle and to reduce the Many to the One. In the same way, and from the same motive, that private war was to be banished from the feudal class in the country, competition--the private war of commerce--was to be eliminated from the trading classes in the towns. Nor was the attack on competition, any more than the attack on war, so much of a forlorn hope as it may seem to a modern age. Even to-day, custom is still a force which checks the operation of competition, and custom covered a far greater area in the Middle Ages than it does to-day.