Pacem, Dei Munus Pulcherrimum §4

⁴ There is no need from us of long proof to show that society would incur the risk of great loss if, while peace is signed, latent hostility and enmity were to continue among the nations. There is not need to mention the loss of all that maintains and fosters civil life, such as commerce and industry, art and literature, which flourish only when the nations are at peace. But what is even more important, grave harm would accrue to the form and essence of the Christian life, which consists essentially in charity and the preaching of which is called the Gospel of peace.