Luke 18

Using the Parable of the Persistent Widow, Jesus taught that we should always pray and not lose heart.  If an unjust judge would grant the widow's request for justice merely because of her persistence; then, much more so would our Righteous God grant justice in answer to the prayers of His people. Then, using the Parable of the Pharisee and the Tax Collector, Jesus taught that "all those who exalt themselves will be humbled, and those who humble themselves will be exalted." (vs 14b).  And, He encouraged the people to "receive the Kingdom of God like a child", with humility, trust, and sincerity.  This passage is a reminder to continually pray, to not give up, and to approach God in humility and trust.

In His conversation with the rich ruler, Jesus pointed out that "No one is good—except God alone".  So when Jesus said "what is impossible with man is possible with God", He was emphasizing that while salvation is impossible by man's own efforts, it is possible through God.   Sorrowfully, the rich ruler chose earthly wealth over kingdom treasures.

When Peter said, "We have left all we had to follow you!" in contrast to the rich ruler, Jesus reassured His disciples that they will be rewarded for their sacrifice.  But, Jesus also showed them that He was the ultimate example of sacrifice, for He was to die on the Cross to fulfill all prophecies as the Messiah.  Though the disciples did not understand what Jesus was saying that that time, they would later; and because they had heard it, it was also preparation for when they faced the actual events surrounding the crucifixion.

Also in contrast to the rich ruler, the blind man who Jesus healed, recognized Him as the Son of David or the Messiah, and chose to follow Jesus, praising God.  His faith saved him.