The disciples were confused. They had thought that Jesus might be the Messiah, but the religious scholars said that Elijah had to come first as Malachi had prophesied: "See, I will send the prophet Elijah to you before that great and dreadful day of the Lord comes. He will turn the hearts of the parents to their children, and the hearts of the children to their parents; or else I will come and strike the land with total destruction." (Malachi 4:5-6). Then, at the transfiguration, Elijah appeared and was quite recognisable alongside Moses. Was this what the Rabbis were talking about?
 
Jesus affirmed Malachi's prophecy. He said that the last prophetic words in the Bible of their day would be fulfilled. In fact, they had already been fulfilled by John the Baptist, although nobody recognised his prophesied role. Jesus had previously explained that in Matthew 11:11-14, but the disciples did not understand. However, they had now seen Elijah and realised that his ministry was in the past. There was no need to make a shelter for him to stay; the focus now was on the ministry of Jesus to bring salvation.
 
The pattern which Jesus would follow had already been demonstrated by John the Baptist who was arrested, put in prison and died in an unjust execution. Jesus wanted His disciples to be prepared for the immediate future of His own suffering, and also to be able to lead the church through difficult periods of persecution (including the violent death that many of them would face).
 
Nothing happens 'by accident' and the Lord lets us see ahead as far as is helpful for us. John the Baptist was prophetically prepared for his role in bringing people to repentance. His death was also prophetic, to let the disciples see that the cruelty of men could not obstruct the work of God but rather focus it upon Jesus. In our lives too, the Sovereign Lord is going to fulfil His plan and will use us in one way or another to achieve it. John had been a willing participant and so was Jesus, and the apostles after Him. Will you allow the Lord to use you in whichever way He shall choose?