I believe BlueBird is making refernce to some type of Biblical numerology. The numbers repeat in the Bible - 3, 7, 12, 40 and so on. There is symbolic significance to these numbers.
"40 THE NUMBER OF PROBATION OR TRIAL. The Israelites wandered for 40 years (Deut. 8:2-5). Moses was on the mount for 40 days (Exodus 24:18); 40 days of Jonah and Nineveh (Jonah 3:4). Jesus was tempted for 40 days (Matt. 4:2)."
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