In 1658 he assisted Baxter to draw up the "Fundamentals of Religion."
Caspar Koolhaes, the heroic minister of Leiden - its first lecturer, too, in divinity - pleaded against a too rigid uniformity, for such an agreement on "fundamentals" as had allowed Reformed, Lutherans and Anabaptists to unite.
Theoretical conceptions were revived by Stahl, who held that acids were the fundamentals of all salts, and the erroneous idea that sulphuric acid was the principle of all acids.
But Sauveur fixed the limiting number of beats for the discord far too low, and again he gave no account of dissonances such as the seventh, where the frequency of the beats between the fundamentals is far beyond the number which is unpleasant.
At the time of the Reformation, the reformers, with their strong sense of the crucial importance of faith, emphasized the action of the individual in the service, and therefore laid it down as a rule that confirmation should be deferred till the child could learn a catechism on the fundamentals of the Christian faith, which Calvin thought he might do by the time he was ten.