Another result which may fairly be attributed to the ascetic teachings of the church is the slow growth of population during the mediæval period. Notwithstanding the gross and flagrant disregard of the rule, it was impossible to immure in convents men and women by the hundred thousand during successive generations without retarding greatly the rate of increase of the species. The rudeness of the arts and sciences, war, pestilence and famine were doubtless efficient causes, yet were they less efficient than enforced celibacy. This is evident when we see the rapid rate of growth established on the abrogation or even relaxation of the rule. The suppression of the monastic orders in France followed soon after the reforms by which Joseph II. discouraged them throughout the Austrian empire, and the result is visible in the enormous increase of European population which followed, notwithstanding the fearful destruction of life in the Napoleonic wars. It is calculated that in 1788 Europe numbered 144,561,000 souls, which within fifty years had been augmented to 253,622,000, or about seventy-five per cent. Of late years the birth-rate has decreased in consequence of the severity of conscription in the military monarchies, but the enormous growth in the half-century following the French Revolution is the best commentary on the influences which for so many ages kept the population almost stationary.[894] * * * * * It required the unbelief of the fifteenth century to give free rein to the rising commercial energies and the craving for material improvement that paved the way for the overthrow of ascetic sacerdotalism. The fearful corruptions of the church, which indirectly caused and accompanied that awakening of the human mind, will be alluded to hereafter when we come to consider the movements leading to the great Protestant Reformation. At present we must turn aside for a moment to consider one or two external developments of the religious activity of the Middle Ages. XXII. THE MILITARY ORDERS. The Military Orders were the natural expression of the singular admixture of religious and warlike enthusiasm, reacting on each other, which produced and was fostered by the Crusades. When bishops considered that they rendered a service acceptable to God in leading vast hosts to slaughter the Paynim, it was an easy transition for soldiers to turn monks, and to consecrate their swords to the bloody work of avenging their Redeemer.