I recall once during a moral lesson in the holy city of Qom,Imam said: "Those who walk on the path of self-purification will sometimes experience openings of light. The more this opening is protected, the more it will grow." After the session I asked him how to maintain that state and that light. He replied: "It is maintained through connection with God and remembrance of God. One should remember God as much as possible."
(Impressions from the Life of Imam Khomeini, Vol. 5, p. 183)