After Descartes had put forth his propositions, nothing appeared fair or true to the inquiring spirit of man but what could be proved by unanswerable demonstration,--all belief in authority passed away; science assumed a new dominion. The divines, also, once her severe rulers,--even Luther had placed the words of Holy Scripture above the human reason,--now found that natural theology was the ally of revelation. Young theologians eagerly sought in this philosophy new supports to their faith. The necessity and wisdom of a Creator were demonstrated from the movements of the stars, the volcanic fires, or the convolutions of a snail's shell. On the other hand, there was no lack of men who denied the creating power of a personal God and the immortality of the soul. But against such isolated deists and atheists, most of the philosophers, and the Christian piety of the great mass of the people, rose in arms. The great German philosophers who, at the beginning of the eighteenth century, were the leaders of this movement, carried a holy fervour into the various circles of German life. Leibnitz, the great creative intellect of his time, a wonderful mixture of elastic pliancy and firm tranquillity, of sovereign certainty and tolerant geniality, worked, by his countless monographs and endless letters, especially on the leaders of the nation and on foreigners, on princes, statesmen, and scholars, opening a path on all sides, and hastening forward to disclose the widest prospects. Besides him, Thomasius, spiritual, emotional, combative, and greedy of approbation, excited even the indifferent and insignificant, by his noisy activity, to take a part in the struggle. As the first German journalist, he contended through the press, both jestingly and in earnest--now in alliance with the Pietists against intolerant orthodoxy, now as opponent of fanatical revivals, for toleration and pure morality against every kind of superstition and fanaticism. Lastly, the younger Christian Wolf, the great professor; he was a methodical, clear, and sober teacher, who, during long years of useful activity, drew up a system and founded a school. A period such as this, in which the great discoveries of individuals inspired their numerous disciples with enthusiasm, is a happy period for millions who perhaps have no immediate share in the new acquisition. Somewhat of apostolical consecration seems to rest upon the first efforts of a school. What has been progressively formed in the soul of a teacher, painfully amidst inward struggles, works on young souls as something great, firm, and elevating. With enthusiasm and Pietism is united the impulse to work out by self-exertion the new acquisition. Rapid is the spread of theorems among the people; they work not only on the individual sciences, but on all the tendencies of the practical mind, on lawgiving, statesmanship, household regulations, and family training; in the studio and workshop of the artist, and handicraftsman.