But, on the other hand, those whom imperfection or age debars from the office of preaching, and yet precipitancy impells to it, are to be admonished lest, while rashly arrogating to themselves the burden of so great an office, they cut off from themselves the way of subsequent improvement; and, while seizing out of season what they are not equal to, they lose even what they might at some time in due season have fulfilled; and be shown to have justly forfeited their knowledge because of their attempt to display it improperly.
They are to be admonished to consider that young birds, if they try to fly before their wings are fully formed, are plunged low down from the place whence they fain would have risen on high. They are to be admonished to consider that, if on new buildings not yet compacted a weight of timbers be laid, there is built not a habitation, but a ruin. They are to be admonished to consider that, if women bring forth their conceived offspring before it is fully formed, they by no means fill houses, but tombs.
For hence it is that the Truth Himself, Who could all at once have strengthened whom He would, in order to give an example to His followers that they should not presume to preach while imperfect, after He had fully instructed His disciples concerning the power of preaching, immediately added, But tarry in the city until you are endued with power from on high. For indeed we tarry together in the city, if we restrain ourselves within the enclosures of our souls from wandering abroad in speech; so that, when we are perfectly endued with divine power, we may then go out as it were from ourselves abroad, instructing others also.
Hence through a certain wise man it is said, Young man, speak scarcely in your cause; and if you have been twice asked, let your answer have a beginning. Hence it is that the same our Redeemer, though in heaven the Creator, and even a teacher of angels in the manifestation of His power, would not become a master of men upon earth before His thirtieth year, in order, to wit, that He might infuse into the precipitate the force of a most wholesome fear, in that even He Himself, Who could not slip, did not preach the grace of a perfect life until He was of perfect age.
For it is written, When he was twelve years old, the child Jesus tarried behind in Jerusalem. And a little afterwards it is further said of Him, when He was sought by His parents, They found him in the temple, sitting in the midst of the doctors, hearing them, and asking them questions. It is therefore to be weighed with vigilant consideration that, when Jesus at twelve years of age is spoken of as sitting in the midst of the doctors, He is found, not teaching, but asking questions.
By which example it is plainly shown that none who is weak should venture to teach, if that child was willing to be taught by asking questions, who by the power of His divinity supplied the word of knowledge to His teachers themselves. But, when it is said by Paul to his disciple, These things command and teach: let no man despise your adolescence, we must understand that in the language of Holy Writ youth is sometimes called adolescence. Which thing is the sooner evident, if we adduce the words of Solomon, who says, Rejoice O young man in your adolescence. For unless he meant the same by both words, he would not call him a young man whom he was admonishing in his adolescence.
Source: Pastoral Rule (New Advent)