Jesus continued speaking to His disciples.
8:16 This was a favorite saying of Jesus' (cf. Matt. 5:15; Mark 4:21; Luke 11:33). In view of the context here the lamp refers to a person who has the light of God's Word within him or her. Such a person has a responsibility to let the light illuminate those around him rather than concealing it from them.
8:17 Jesus next commented on the parable of the lamp indicating its significance. Disciples should not suppose that because God had kept the truth that Jesus had revealed to them secret He wanted it to remain hidden. He wanted it declared publicly now.
8:18 Jesus concluded by urging His disciples to listen carefully to what He taught them. If they believed what He told them, God would give them more truth. However if they disbelieved, God would remove what truth they thought they had from them.
