Saint Pope Pius X taught:
Distracted with so many occupations, it is easy to forget the things that lead to perfection in priestly life; it is easy [for the priest] to delude himself and to believe that, by busying himself with the salvation of the souls of others, he consequently works for his own sanctification. Alas, let not this delusion lead you to error, because nemo dat quod nemo habet [no one gives what he does not have]; and, in order to sanctify others, it is necessary not to neglect any of the ways proposed for the sanctification of our own selves.
The Pope is the guardian of dogma and of morals; he is the custodian of the principles that make families sound, nations great, souls holy; he is the counsellor of princes and of peoples; he is the head under whom no one feels tyrannized because he represents God Himself; he is the supreme father who unites in himself all that may exist that is loving, tender, divine.
It seems incredible, and is even painful, that there be priests to whom this recommendation must be made, but we are regrettably in our age in this hard, unhappy, situation of having to tell priests: love the Pope!
And how must the Pope be loved? Non verbo neque lingua, sed opere et veritate. [Not in word, nor in tongue, but in deed, and in truth - 1 Jn iii, 18] When one loves a person, one tries to adhere in everything to his thoughts, to fulfill his will, to perform his wishes. And if Our Lord Jesus Christ said of Himself, "si quis diligit me, sermonem meum servabit," [if any one love me, he will keep my word - Jn xiv, 23] therefore, in order to demonstrate our love for the Pope, it is necessary to obey him.
Therefore, when we love the Pope, there are no discussions regarding what he orders or demands, or up to what point obedience must go, and in what things he is to be obeyed; when we love the Pope, we do not say that he has not spoken clearly enough, almost as if he were forced to repeat to the ear of each one the will clearly expressed so many times not only in person, but with letters and other public documents; we do not place his orders in doubt, adding the facile pretext of those unwilling to obey - that it is not the Pope who commands, but those who surround him; we do not limit the field in which he might and must exercise his authority; we do not set above the authority of the Pope that of other persons, however learned, who dissent from the Pope, who, even though learned, are not holy, because whoever is holy cannot dissent from the Pope.
This is the cry of a heart filled with pain, that with deep sadness I express, not for your sake, dear brothers, but to deplore, with you, the conduct of so many priests, who not only allow themselves to debate and criticize the wishes of the Pope, but are not embarrassed to reach shameless and blatant disobedience, with so much scandal for the good and with so great damage to souls.
Saint Pius X
Allocution Vi ringrazio to priests on the 50th anniversary of the Apostolic Union