What does Luke 8:17 mean?

The meaning of this verse depends on which of two ways the previous verse should be interpreted.

Most likely, the "light" is Jesus' words. He teaches so that people can understand and accept the truth of His message. He teaches in parables to test people: Will they contemplate what He says, accept it, and let it produce fruit in their lives? Or will the distractions of the world draw them away from real understanding?

For those who listen carefully to Jesus' parables, the light of His words will be "made manifest," meaning it will come to be known, or uncovered, or revealed. Those who don't seek out Jesus' meaning are like those who put the light under a jar or a bed. They will understand Jesus' words at the final judgment.

The next verse supports this interpretation. Those who have some understanding of who Jesus is and what He says will likely continue to listen carefully and receive "more"—wisdom and blessings. Those who have truly little understanding are like the first three soils in the parable. Whatever understanding they had will be lost as they follow their distractions. It is these Jesus describes when He justifies His use of parables, that "seeing they may not see, and hearing they may not understand" (Luke 8:10).

Another interpretation is that the "light" represents the good "fruit" that results when we listen to Jesus (Galatians 5:22–23). When we hear or read His message, we need to be like the good soil—readily accept His truths, nurture them, and allow the Holy Spirit to produce good results in our lives. Those who do not listen to Jesus will have bad fruit (Galatians 5:17–21). Either way, the fruit will inevitably reveal whether they listened to Christ or not. This interpretation seems to lean too heavily on a similar but different parable Jesus gives in Matthew 5:14–16.