The "doctors of the law" in the Bible knew that certain events had to take place in order to verify the timing of judgment predicted to come at the end of white rule.
When Jesus of 2,000 years ago made his appearance in an attempt to save them, those who were familiar with scripture and its timing studied the resurrection and judgment teachings of Jesus, but found that the timing was suspect.
Considering that there were a few gaps or events missing from the time, they constantly second guessed him and his disciples. One such incident happened when the disciples were out teaching and were approached by the Jewish Scribes, who rejected their claim, because Elijah was to be raised just before the great and dreadful day of the Lord. When the disciple went back to Jesus to report of their encounter, they asked Jesus, "Why do the Scribes say that Elijah must first come?