20 In declaring, dearly Beloved Sons and Venerable Brothers, that the existence of Diocesan Associations can only be permitted by Us, We must frankly avow that by this statement We have wished to abstain from commanding you in a formal manner to create and to establish them. However, We desire their existence, and We pray you in Jesus Christ, inspired by that feeling of filial love which you have for Us and by the ardent desire which consumes you to protect the discipline, unity, and peace of the Church, to give a trial to these Diocesan Associations. In doing this, you will demonstrate that you are filled with the selfsame spirit of generosity and of filial deference for us that you had for Our Predecessor of saintly memory, Pius X. For God will have mercy on all "who have done all this together, and have craved mercy of the Lord" (II Machabees xiii, 12); "and God is faithful, who will not suffer you to be tempted above that which you are able; but will make also with temptation issue, that you may be able to bear it." (1 Cor . x, 13)
Source: Maximam Gravissimamque (Vatican.va)