These sayings of Jesus (Lk 11: 33-36) were originally independent, but were grouped together and added to Jesus’ warning in the preceding section (Lk 11: 14-32) by the evangelist. Their source is ‘Q’ (Cf. Mt 5: 15; 6: 22-23).
The parabolic saying about light (Lk 11: 33) in its present context shows that Jesus himself is the light or lamp lit and placed in the sight of all, and therefore, it is not necessary to have any other ‘heavenly sign’ to prove his credentials (Note: that in Lk 8: 16, a similar saying referred to Jesus’ teaching). Thus Jesus, the light, is certainly the “something greater” than Solomon and Jonah. Luke had already shown that Jesus is the ‘light’ in the first part of his gospel (Lk 2: 32). The light that Jesus is, is not covered (Lk 11: 33). If the people do not see the light it is because their eye is not healthy; they are spiritually blind. The phrase, “those who enter” may refer to those who would become converts. The saying implicitly calls the disciples to become light unto others in their own mission. They must be totally open to the WORD and live by it. Only to the extent that ‘no part’ of their body is in darkness that they will be able to be illumined by the true light of Jesus and the Word proclaimed by him.
Israel was called to be the light of God in the midst of the nations (Cf. Is 49: 6). But, it is now Jesus who fulfils that mission by being the light in the midst of his generation.