Luke focused the disciples' question on the one parable he recorded so far. Matthew and Mark had them asking Jesus why He was speaking to the people in parables (plural). "Mysteries"were revelations previously unknown about the kingdom (cf. Dan. 2:20-23, 28-30). The Greeks had their mystery religions the secrets of which only the initiated knew. Consequently Luke's original readers would have had no trouble understanding Jesus' meaning. The parables intentionally revealed some truth to everyone who heard them, but only Jesus' disciples could understand the deeper significance of what they taught. One of the principles of spiritual growth is that when a person responds positively to revelation, God gives him or her the ability to understand more truth. However when one does not respond positively, God hides further truth from him or her (v. 18; Isa. 6:9; cf. Exod. 8:32; 9:12; Rom. 9:17-18). "That"indicates purpose more than result (v. 10).