31 To return to a subject which We discussed above. If it is necessary, Venerable Brothers and Beloved Sons, in the cities where you have your residences and in other more important centers, to erect large churches and other mission buildings, you must, however, avoid building churches or edifices that are too sumptuous and costly as if you were erecting cathedrals and episcopal palaces for future dioceses. This type of structure will come in due time and when the need really exists. Assuredly, you are aware of the fact that there exist dioceses which have been canonically erected, and that a long time ago, and yet only now are they constructing or have just finished the construction of churches and buildings of this kind. Moreover, it would be neither right nor advisable to bring together, really to crowd together, in one of the principal cities or in the town where you reside the various institutions erected for the welfare of both the souls and bodies of the people. If such institutions are really large and important they will need on the spot both your presence and that of the missionaries, and thus your visits in the interests of the propagation of the faith to the remainder of the territory committed to your charge will necessarily cease. Since mention has been made of such good works, over and above hospitals and institutions for the care of the sick and for the distribution of medicines, and elementary schools which you ought to open in every town, it is important that you found other types of schools for the young people who do not intend to take up agriculture, and thus by these schools open the way to them to acquiring a higher education, particularly in the arts and sciences and in the professions. We also exhort you not to neglect in this work of education the better classes, especially the rulers of the locality and their children. It is beyond question that the word of God and its ministers are received more readily by the poor and humble than by the proud and rich. It is also true that Jesus Christ said to Himself, "the spirit of the Lord hath sent me to preach the Gospel to the poor." ( Luke iv, 18) Yet, at the same time, We must not forget what St. Paul writes: "to the wise and unwise, I am a debtor." ( Romans i, 14) Both history and experience teach that when once the rulers of a people have been converted to Christianity, the common people follow closely in the footsteps of their leaders.
Source: Rerum Ecclesiae (Vatican.va)