Mark 4:21

(non occ.) After the question of the disciples concerning the parable, and its explanation, He well subjoins, And he said unto them, Is a candle brought, &c. As if he said, A parable is given, not that it should remain obscure, and hidden as if under a bed or a bushel, but that it should be manifested to those who are worthy. The candle within us is that of our intellectual nature, and it shines either clearly or obscurely according to the proportion of our illumination. For if meditations which feed the light, and the recollection with which such a light is kindled, are neglected, it is presently extinguished. (in Matt. Hom. 15) Or else, There is nothing hid; as if He said, If ye conduct your life with care, accusation will not be able to obscure your light.

(in Marc. i. 20) Or, because the time of our life is contained under a certain measurement of Divine Providence, it is rightly compared to a bushel. But the bed of the soul is the body, in which it dwells and reposes for a time. He therefore who hides the word of God under the love of this transitory life, and of carnal allurements, covers his candle with a bushel or a bed. But he puts his light on a candlestick, who employs his body in the ministry of the word of God; therefore under these words He typically teaches them a figure of preaching. Wherefore it goes on, For there is nothing hidden, which shall not be revealed, nor is there any thing made secret, which shall not come abroad. As if He said, Be not ashamed of the Gospel, but amidst the darkness of persecution raise the light of the word of God upon the candlestick of your body, keeping fixedly in your mind that day, when the Lord will throw light upon the hidden places of darkness, for then everlasting praise awaits you, and everlasting punishment your adversaries.

Or else the Lord warns His disciples to be as light, in their life and conversation; as if He said, As a candle is put so as to give light, so all will look to your life. Therefore be diligent to lead a good life; sit not in corners, but be ye a candle. For a candle gives light, not when placed under a bed, but on a candlestick; this light indeed must be placed on a candlestick, that is, on the eminence of a godly life, that it may be able to give light to others. Not under a bushel, that is, in things pertaining to the palate, nor under a bed, that is, in idleness. For no one who seeks after the delights of his palate and loves rest can be a light shining over all.

Or else the candle is the discourse concerning the three sorts of seed. The bushel or the bed is the hearing of the disobedient. The Apostles are the candlestick, whom the word of the Lord hath enlightened.