Summi Pontificatus §33

³³ It is true that even when Europe had a cohesion of brotherhood through identical ideals gathered from Christian preaching, she was not free from divisions, convulsions and wars which laid her waste; but perhaps they never felt the intense pessimism of today as to the possibility of settling them, for they had then an effective moral sense of the just and of the unjust, of the lawful and of the unlawful, which, by restraining outbreaks of passion, left the way open to an honorable settlement. In Our days, on the contrary, dissensions come not only from the surge of rebellious passion, but also from a deep spiritual crisis which has overthrown the sound principles of private and public morality.