by its own powers, these thinkers believed that it was soluble by the gradual triumph of reason over prejudice and knowledge over ignorance.  Violent revolution was far from their thoughts; by the diffusion of knowledge they hoped to create a public opinion which would compel governments to change the tenor of their laws and administration and make the happiness of the people their guiding principle.  The optimistic confidence that man is perfectible, which means capable of indefinite improvement, inspired the movement as a whole, however greatly particular thinkers might differ in their views.

Belief in Progress was their sustaining faith, although, occupied by the immediate problems of amelioration, they left it rather vague and ill-defined.  The word itself is seldom pronounced in their writings.  The idea is treated as subordinate to the other ideas in the midst of which it had grown up:  Reason, Nature, Humanity, Illumination (lumieres).  It has not yet entered upon an independent life of its own and received a distinct label, though it is already a vital force.

In reviewing the influences which were forming a new public opinion during the forty years before the Revolution, it is convenient for the present purpose to group together the thinkers (including Voltaire) associated with the Encyclopaedia, who represented a critical and consciously aggressive force against traditional theories and existing institutions.  The constructive thinker Rousseau was not less aggressive, but he stands apart and opposed, by his hostility to modern civilisation.  Thirdly, we must distinguish the school of Economists, also reformers and optimists, but of more conservative temper than the typical Encyclopaedists.

2.

The Encyclopaedia (1751-1765) has rightly been pronounced the central work of the rationalistic movement which made the France of 1789 so different from the France of 1715. [Footnote:  The general views which governed the work may be gathered from d’Alembert’s introductory discourse and from Diderot’s article Encyclopedie.  An interesting sketch of the principal contributors will be found in Morley’s Diderot, i. chap. v.  Another modern study of the Encyclopaedic movement is the monograph of L. Ducros, Les Encyclopidistes (1900).  Helvetius has recently been the subject of a study by Albert Keim (Helvetius, sa vie et son oeuvre, 1907).  Among other works which help the study of the speculations of this age from various points of view may be mentioned:  Marius Roustan, Les Philosophes et la societe francaise au xviii siecle(1906); Espinas, La Philosophie sociale du xviii siecle et la Revolution (1898); Lichtenberger, Le Socialisme au xviii siecle(1895).  I have not mentioned in the text Boullanger (1722-1758), who contributed to the Encyclopaedia the article on Political Economy (which has nothing to do with economics but treats of ancient theocracies); the emphasis laid on his views on progress by Buchez (op. cit. i.  III sqq.)