Pacem in Terris §155

¹⁵⁵ The definition of these degrees and forms is all the more difficult in an age such as ours, driven forward by a fever of activity. And yet this is the age in which each one of us is required to make his own contribution to the universal common good. Daily is borne in on us the need to make the reality of social life conform better to the requirements of justice. Hence Our sons have every reason for not thinking that they can relax their efforts and be satisfied with what they have already achieved.