title over discovered lands. He elaborated up to eight legitimate titles of dominion. The first and perhaps most fundamental relates to communication between people, who jointly constitute a universal society. Ius peregrinandi et degendi is the universal right to travel and do commerce in all parts of the earth, independently of who governs or what is the religion of the territory. For him, if the "Indians" of the Americas would not permit free transit, the hindered parties had the right to defend themselves and to remain in land obtained in such a war of self-defense. The second form of legitimate title over discovered lands referred to the right of the Spanish to preach and proselytize. The Indians could voluntarily refuse conversion, but forbidding missionaries would make the matter analogous to the first case. Nonetheless, Vitoria noted that although this can be grounds for a just war, it is not necessarily prudent because of the resulting death and destruction. The other cases of this casuistry are: If the pagan sovereigns force converts to return to idolatry. If there come to be a sufficient number of Christians in the newly discovered land that they wish to receive from the Pope a Christian government. In the case of overthrowing a tyranny or a government that is harming innocents (e.g. human sacrifice) If associates and friends have been attacked—as were the Tlaxcaltecas, allied with the Spanish but subjected, like many other people, to the Aztecs—once again, this could justify a war, with the ensuing possibility of legitimate conquest as in the first case. The final "legitimate title" although qualified by Vitoria himself as doubtful, is the suffering of the foreign population from lack of just laws, magistrates, agricultural techniques, etc. In any case, title taken according to this principle must be exercised with Christian charity and for the advantage of the Indians. Emperor Charles V, then ruler of Spain, took offense to this doctrine of "legitimate" and "illegitimate" titles purporting to limit his prerogatives, and he tried without success to stop its promulgation. Economics The School of Salamanca has been described as the "first economic tradition" in the field of economics. This put the origins of economic theory on Europe's mainland, prompting a reassessment of the entire history of the discipline. Much attention has been drawn to the economic thought of the School of Salamanca by Joseph Schumpeter's History of Economic Analysis (1954). It