Born of Protestant parents in the south-west of France, Bayle was educated at Toulouse, became Catholic, lapsed, fled to Geneva, and then became professor in the Protestant academy at Sedan in northern France from 1675 to 1681, in which year he again fled from religious persecution to Holland. He lived in Rotterdam for the rest of his life, writing and corresponding with the philosophers and theologians of his time. His personal experience made him an impassioned defender of religious toleration, and an opponent of pretensions of reason in theological and metaphysical matters. Much of his energy was spent undermining the orthodox Calvinism of his time, represented by his one-time teacher, Jurieu, ostensibly on behalf of a true Calvinism based on revelation, but arguably in favour of religious scepticism. His attitude is captured in the remark quoted by Gibbon: ‘I am most truly a Protestant; for I protest indifferently against all systems and all sects.’ Bayle's critical and sceptical attitudes gained full expression in his masterpiece, the Dictionnaire historique et critique (1695–7, trs. as An Historical and Critical Dictionary, 1710). In this work, the ‘arsenal of the Enlightenment’, Bayle combines historical treatments of religious and philosophical figures (most notably secondary and neglected ones) with a pervading scepticism. The dictionary is often witty and profane, and in its own time was notorious for advocating the complete separation of religion and morality, and for gleefully depicting the immoral lives of many people important to the Church. But its more substantial philosophical content made the Dictionary a sourcebook for all 18th-century discussions of difficulties with the Cartesian world view. It contains many of the arguments later deployed by Berkeley and Hume, and is undoubtedly the most important contribution to scepticism since Sextus Empiricus. Famous articles included those on Pyrrho, Rorarius (which heads an attack on Leibniz's theory of pre-established harmony), and Zeno of Elea (see Bayle's trilemma).