peculiar dispositions and circumstances that they infallibly, though at the same time quite freely, yield themselves to its influence. This mediatizing system was known by the name of "congruism." Philosophy of law Here, Suárez's main importance stems probably from his work on natural law, and from his arguments concerning positive law and the status of a monarch. In his massive work, Tractatus de legibus ac deo legislatore (1612), he is to some extent the precursor of Grotius and Pufendorf, in making an important distinction between natural law and international law, which he saw as based on custom. Though his method is throughout scholastic, he covers the same ground, and Grotius speaks of him with great respect. The fundamental position of the work is that all legislative as well as all paternal power is derived from God, and that the authority of every law stems ultimately from God's eternal law. Suárez denies the patriarchal theory of government and the divine right of kings founded upon it, doctrines popular at that time in England and to some extent on the Continent. He argued against the sort of social contract theory that became dominant among early-modern political philosophers such as Thomas Hobbes and John Locke, but some of his thinking, as transmitted by Grotius, found echoes in later liberal political theory. He argued that human beings have a social nature bestowed upon them by God, and this includes the potential to make laws. However, when a political society is formed, the authority of the state is not of divine but of human origin; therefore, its nature is chosen by the people involved, and their natural legislative power is given to the ruler. Because they gave this power, they have the right to take it back and to revolt against a ruler, only if the ruler behaves badly towards them, and they must act moderately and justly. In particular, the people must refrain from killing the ruler, no matter how tyrannical he may have become. If a government is imposed on people, on the other hand, they have the right to defend themselves by revolting against it and even kill the tyrannical ruler. Though Suárez was greatly influenced by Aquinas in his philosophy of law, there are some notable differences. Aquinas broadly defined "law" as "a rule and measure acts, whereby man is induced to act or is restrained from acting" (ST 1-11, qu.