During the century which followed, mental activity found employment in other channels in connexion with the political struggles which resulted from the religious changes. But the seventeenth age was another of those epochs which form crises in the history of the human mind. The reconstruction at that time of the methods on which science depends, by Bacon from the empirical side, by Descartes from the intellectual, created as great a revolution in knowledge as the Renaissance had produced in literature or the Reformation in religion; and a body of materials was presented from which philosophers ventured to criticise the Bible and the dogmatic teaching of the Church. This fourth great period of free thought, which extends to the present time, has been marked by more striking events than former ones.(70) Though the movement relates to a similar sphere, the history is rendered more complex by union with literature, and connexion as cause or effect with social changes, as well as by the reciprocal operation of its influence in different countries. Language, which is always a record of opinion, popular or scientific,(71) classifies the forms of this last great movement of free thought under three names, viz. Deism in England in the early part of the eighteenth century; Infidelity in France in the latter part of it; and Rationalism in Germany in the nineteenth; movements which exhibit characteristics respectively of the three nations, and of their intellectual and general history. English Deism, the product of the reasoning spirit which was stimulated by political events, directed itself against the special revelation of Christianity from the stand-point of the religion of natural reason, and ran a course parallel with the gradual emancipation of the individual from the power of the state. French infidelity, breathing the spirit of materialist philosophy, halted not till it brought its devotees even to atheism, and mingled itself with the great movements of political revolution, which ultimately reconstituted French society. German Rationalism, empirical or spiritual,(72) in two parallel developments, the philosophical and the literary, neither coldly denied Christianity with the practical doubts of the English deists, nor flippantly denounced it as imposture with the trenchant and undiscriminating logic of the French infidels; but appreciating its beauty with the freshness of a poetical genius, and regarding it as one phase of the religious consciousness, endeavoured, by means of the methods employed in secular learning, to collect the precious ideas of eternal truth to which Christianity seemed to it to give expression, and by means of speculative criticism to exhibit the literary and psychological causes which it supposed had overlaid them with error.