Mark 4:21

Doth a candle come in, i.e., is it brought into a house, to be put under a bushel or under a bed? That it should be hidden under a vessel? No! but that it should be exposed publicly, and give light to all. Christ signified by this parable that it was not His will that the mysteries of this parable and the other doctrines of the Gospel should be concealed and hidden, but that His disciples should unfold them in their time, and communicate to others who at that time were not able to receive them. It was His will that they should publish and preach them openly. This is plain from what follows. Ver. 22. For there is nothing hid which shall not be made manifest; neither was it made secret, but that it may come abroad. This is the Greek and Latin reading. Although the doctrine of the Gospel and My deeds and words are as yet hidden and secret, I do not wish them always to remain so. At the proper time they must be openly proclaimed by you, 0 My disciples. So SS. Jerome and Bede. This is what Christ says in S. Matt. x. 27, What I say unto you in darkness, that speak ye in light, &c. Ver. 24. And He said unto them, Take heed what ye hear. The meaning, says Euthymius, is, "Attend to the things which ye hear of Me, that ye may understand them, and commit them to memory, that when the proper time shall arrive ye may communicate them to others." And He assigns the reason, which, as Theophylact says, is, "That none of My words may escape you." Hear Bede, "He teaches us carefully to hear His words, in such manner that we should carefully digest them in our hearts, and be able to bring them forth for the hearing of others."

In what measure you shall mete, it shall be measured to you again, and more shall be given to you. He means, if ye largely and copiously communicate and preach My doctrine to others, I also will copiously impart to you more understanding and greater wisdom, grace, and glory, as a recompense and reward to you. Thus fountains, the more they pour out above, the more they receive from below. Therefore, let preachers, teachers, and catechists learn from this promise of Christ, that the more pains they bestow in teaching others, the more grace and wisdom they will receive from Christ themselves, according to the words, "He that soweth sparingly shall reap also sparingly, and he that soweth in blessings," i.e., abundantly, "shall reap also in blessings" (2Co 9:6), Vulg. Ver. 25. For he that hath, to him shall be given; and he that hath not, that also which he hath shall be taken away from him. Hath, that is, uses, and shows that he hath by using. For such a one hath indeed, but he who useth not a gift or grace hath it but in name. This is what theologians say, that he who uses his grace hath it in a second act; but he who uses it not hath it only in the first act, that is, in power and possession. The meaning therefore is, he who, by study or by imparting to others, uses learning given him by God, an increase of learning shall be given; but from him who uses not his learning, shall God take it away.