Luke 8 16 “No one, when he has lit a lamp, covers it with a vessel or puts it under a bed, but sets it on a lampstand, that those who enter may see the light. 17 For nothing is secret that will not be revealed, nor anything hidden that will not be known and come to light. 18 Therefore take heed how you hear. For whoever has, to him more will be given; and whoever does not have, even what he seems to have will be taken from him.”19 Then His mother and brothers came to Him, and could not approach Him because of the crowd. 20 And it was told Him by some, who said, “Your mother and Your brothers are standing outside, desiring to see You.”21 But He answered and said to them, “My mother and My brothers are these who hear the word of God and do it.”

He typically sets forth the boldness of preaching, that no one should, through fear of fleshly ills, conceal the light of knowledge. For under the names of vessel and bed, he represents the flesh, but of that of lantern, the word, which whosoever keeps hid through fear of the troubles of the flesh, sets the flesh itself before the manifestation of the truth, and by it he as it were covers the word, who fears to preach it. But he places a candle upon a candlestick who so submits his body to the service of God, that the preaching of the truth stands highest in his estimation, the service of the body lowest.

(St Augustine)