Read Part 1, Part 2, Part 3, Part 4, Part 5.

"And, behold, there appeared unto them Moses and Elias talking with Him." Matthew 17:3
"And there appeared unto them Elias with Moses: and they were talking with Jesus." Mark 9:4
"And, behold, there talked with him two men, which were Moses and Elias:" Luke 9:30

"For to this end Christ both died, and rose, and revived, that He might be Lord both of the dead and living." Romans 14:9

Moses represents the dead.
Elijah represents the living.
Christ Jesus is the Lord of the dead and living.