Matthew 17:1 says, And after six days Jesus taketh Peter, James, and John his brother, and bringeth them up into an high mountain apart,  After six days, Jesus took Peter, James and John up on a high mountain with Him.  We are not told what happened in that week, but I believe that we can safely say that Jesus was still preparing His disciples for His coming death, burial and resurrection.  I do not know why Jesus took only these three disciples, nor how the other disciples felt about being left behind.  What we must acknowledge is that not everyone is called to follow Jesus in the exact same way, and we must never feel jealous if someone else seems to do something for Jesus that seems to bring them more glory in the eyes of the world.  The opposite is also true.  Peter, James and John could not go down the mountain claiming to be morally superior to the other disciples, and no matter what we do for God today, we can never feel morally superior to other Christians.  Verse two states, And was transfigured before them: and his face did shine as the sun, and his raiment was white as the light.  These three disciples got at least a glimpse of Who Jesus really was.  His face shined like the sun and His clothes were as white as light.  I cannot imagine what Peter, James and John felt, but they must have been overwhelmed.  Verse three states, And, behold, there appeared unto them Moses and Elias talking with him.  Moses and Elijah appeared talking with Jesus.  I personally do not believe that they returned to earth, but that these three got a glimpse into Heaven.  Verse three states, Then answered Peter, and said unto Jesus, Lord, it is good for us to be here: if thou wilt, let us make here three tabernacles; one for thee, and one for Moses, and one for Elias.  Peter was ready to build tabernacles for Moses, Elijah and Jesus.  Peter said this would be a good thing, but none of the three could stay long in this world.  Moses and Elijah were already in heaven, and Jesus would soon be.  We cannot keep Jesus to ourselves, but have a responsibility to go out into the world with His message of salvation.  Verse five declares, While he yet spake, behold, a bright cloud overshadowed them: and behold a voice out of the cloud, which said, This is my beloved Son, in whom I am well pleased; hear ye him.  Even as Peter stated his plan, a bright cloud overshadowed them.  Then the voice of God came down, telling these three disciples that Jesus was God's beloved Son, with whom God was well pleased, and that they should listen to Jesus.  Just like Peter, instead of attempting to tell Jesus what to do, we need to simply listen to what He wants us to do.  Verse six says,  And when the disciples heard it, they fell on their face, and were sore afraid.  I am not sure how we would react if we heard a voice from heaven, declaring that Jesus was the beloved Son of God.  The three disciples there fell to their faces and were very afraid.  God does speak to each individual, maybe not in such dramatic fashion, but He does call everyone to Him, through His beloved Son Jesus.  Verse seven declares, And Jesus came and touched them, and said, Arise, and be not afraid.  Jesus touched them, told them to arise and to not be afraid.  When Jesus comes into our life today, if we listen to and accept His call, then we no longer need to be afraid.  We have everlasting security through our faith in Christ.  Verse eight states, And when they had lifted up their eyes, they saw no man, save Jesus only.  When they looked up, they didn't see the source of the voice, only Jesus.  When we come to God, we can only come by seeing Jesus alone as our Savior and Lord.  Verse nine says, And as they came down from the mountain, Jesus charged them, saying, Tell the vision to no man, until the Son of man be risen again from the dead.  When they came down off the mountain, Jesus told Peter, James and John to not tell anyone what they had seen.  We today, since Jesus has completed His redemptive act, are told to go and tell the world about Him.  Verse ten says, And his disciples asked him, saying, Why then say the scribes that Elias must first come?  The disciples questioned Jesus about why the scribes said that Elias, or Elijah, had to come before the Messiah could come.  They were looking for a physical return of Elijah, once more misinterpreting the scripture.  We must be careful that we do not attempt to change what God's word says into what we think it should say.  Verse eleven states, And Jesus answered and said unto them, Elias truly shall first come, and restore all things.  Jesus answered them, just as He will answer our questions today.  Jesus said that Elijah must come first to restore all things, but He was not speaking of a physical return of Elijah.  Verse twelve says, But I say unto you, That Elias is come already, and they knew him not, but have done unto him whatsoever they listed. Likewise shall also the Son of man suffer of them.  Jesus said Elijah had already come, but the people did not recognize or accept him, just as they would fail to recognize Jesus and He would suffer at their hands.  Verse thirteen declares, Then the disciples understood that he spake unto them of John the Baptist.  The disciples, when they asked Jesus about Elijah, were led to the understanding that Jesus was speaking about John the Baptist, who was the one who was like Elijah returning.  When we go to Jesus with a question, if we listen to His answer, we will be left with a clear understanding of what God is really saying to us.  Jesus did not change the scripture, but He gave the disciples a better understanding of what the scripture actually said.  We are never going to be led by God to do anything that goes against the scripture, but by the leadership of the Holy Spirit we will always be led to a clearer understanding of what the scripture does say.