In the passage of scripture of Matthew 13:10-17 the disciples of Jesus came to him and asked  why he had began to speak in parables.  In his answer, Jesus made his disciples to understand three facts about how spiritual truth can be  comprehended:

1. Spiritual truth can only be comprehended when there is a certain willingness to follow what is presented.

2. An unwillingness to accept and an inability to comprehend the spiritual truth that an individual is presented with necessarily leads to a decline in that individual’s spiritual growth.    

3. The parables of the Kingdom of Heaven is God’s way of giving mankind  the  revelation of Jesus Christ as the complete fulfillment of God’s salvation, which the prophets only saw in part.

In essence Jesus was declaring that hearing the message of the kingdom of heaven would necessarily impact men’s soul.  Jesus stated that man‘s knowledge is lessened by rejecting the truth and that their will of men would be hardened against the truth as a result of its’ rejection.  In contrast Jesus states that those (like His disciples)  would grow spiritually as a result of their willingness to receive the truth.  This spiritual growth is summarized as “hearing and seeing” that would lead to conversion and healing.  It is to be understood that the kingdom of heaven is the knowledge and acceptance of Christ’s Lordship in the hearts of men, and it leads to unlocking all the mysteries of salvation.