Mark 4:21

Jesus continued his address to the inquiring disciples (cf. Mark 4:10-20). The lamp would have been a small clay dish with the edges pinched up to form a spout. A small piece of fabric typically hung over the spout from the body of the lamp serving as a wick. These household lamps usually held only a few teaspoons of oil and rested on pieces of wood or plaster protruding from a wall. The basket was a common container that held about a peck (one-quarter bushel).

The lamp seems to represent the illumination that Jesus had just given about the purpose of the parables and the meaning of the parable of the soils. He did not want His disciples to conceal what He had just told them but to broadcast it. In His day this involved revelation about the impending kingdom particularly. In the wider sphere of application it would include all that God has revealed (cf. Psalms 119:105).

Another interpretation sees Jesus as the light that His disciples were not to conceal. [Note: E.g., Wessel, p. 652.] Jesus elsewhere spoke of Himself as the light of the world (John 8:12). Nevertheless in this context the light seems to represent revelation. Light has both metaphorical meanings in Scripture.