In Luke 8:16-18 Jesus follows up his explanation of the Parable of the Sower by giving a picture to inspire his disciples. He has lit a light in his disciples by teaching them about the kingdom; this light is to be shared.
v16,17- Although Jesus speaks in parables, it is nevertheless his ultimate purpose that the light of the gospel be spread in full meaning. He initiates his followers into the knowledge of the mysteries of the kingdom, not for them to hide such knowledge, but to make it known, to all whom they come into contact.
v18- Because it is so necessary for his disciples to be light-bearers, he commands them to see to it that they listen carefully, hear correctly and with full attention so that they will be able to live it with steadfast conviction. Learning the Word of the Gospel was to bear fruit in the lives of disciples, if not, the results would be fatal. Those who hear and live obediently will be given deeper and more intensive insight into the spiritual life and into his Word!