Part — Wouters, Manual of Moral Theology
Part II. On Admission and Preparation for the Reception of Orders
I. No one from among seculars is to be ordained who, in the judgment of his proper Bishop, is not necessary or useful for the churches of the diocese. Yet the Bishop is not prohibited from promoting his own subject who is destined in the future, after legitimate excardination and incardination, for the service of another diocese (canon 969).
II. First tonsure and Orders are to be conferred only on those who have the purpose of ascending to the Presbyterate and whom one may rightly conjecture will someday be worthy priests (canon 973, § 1). Yet an ordained man who refuses to receive higher Orders can neither be compelled by the Bishop to receive them, nor be prohibited from the exercise of the Orders received, unless he is held by a canonical impediment or some other grave cause stands in the way, in the judgment of the Bishop (canon 973, § 2).
III. The Bishop is to confer sacred Orders on no one unless from positive arguments he is morally certain about that person's canonical suitability; otherwise he not only sins most gravely, but also commits himself to the danger of communicating in another's sins (canon 973, § 3). It is said from positive arguments; therefore it does not suffice that nothing is opposed, or that the ordinand has not committed a sin which can be juridically proved. For the rest, these things do not suffice for acquiring moral certainty.
Nor is one to depart from these things on account of a shortage of priests. "Care must be taken," says Benedict XV in his letter to the Bishops of Bolivia,1 "lest those less worthy also be admitted to the priesthood by reason of necessity... Therefore we must weigh not how many, but what kind of sacred ministers we take up; and, after trying all the things which prudence may suggest for fostering the pursuit of the priesthood among youth, let us diligently commend the matter to God, in whose hand it is." Add these words of the Fourth Lateran Council: "It is better... to have fewer ministers, but upright... and useful ones, than more who... will be of no avail."2 Likewise these words of St. Thomas: "God never so deserts His Church that suitable ministers sufficient for the necessity of the people cannot be found, if the worthy were promoted and the unworthy repelled. Even if as many ministers could not be found as there now are, it would be better to have a few good ministers than many bad ones" (Supplement, q. 36, a. 4, ad 1).
But if applicants are superabundant, the Bishop, in order to guard against idleness, should choose the better ones and leave aside the less suitable; and, with the things that must be observed being observed, religious Superiors also can apply these things with respect to those whom they foresee will be almost useless in religion for undertaking priestly offices.
IV. The proper Bishop or major religious Superior can forbid his clerics ascent to Orders for any canonical cause, even occult, and even extrajudicially, with the right of recourse to the Holy See remaining intact, or also to the Moderator General if it is a question of religious whose ascent has been forbidden by the Provincial Superior (canon 970).
V. Care must be taken that those aspiring to sacred Orders be received into the Seminary from tender years; but all are bound to remain there at least through the entire curriculum of sacred theology, unless the Ordinary has dispensed in particular cases for a grave cause, his conscience being burdened. Those who aspire to Orders and legitimately remain outside the Seminary are to be commended to a pious and suitable priest, who is to watch over them and form them to piety (canon 972).
1 August 4, 1918.
2 Chapter 27.