Answer by Kenneth:
1. 40 years, a generation
There is good evidence to show that the number forty represents the time it takes for a generation to pass, with the time the Bible depicts Israel being in the wilderness probably the best evidence for this:
Num 14:34 According to the number of the days in which you spied out the land, forty days, for every day a year, you shall bear your iniquity, forty years, and you shall know my displeasure
Num 32:13 And the Lord’s anger was kindled against Israel, and he made them wander in the wilderness for forty years, until all the generation that had done evil in the sight of the Lord had disappeared.
Josh 5:6 “For the Israelites traveled forty years in the wilderness, until all the nation, the warriors who came out of Egypt, perished, not having listened to the voice of the Lord
Psa 95:10 For forty years I loathed that generation and said, “They are a people whose hearts go astray, and they do not regard my ways.”
With this in mind, other uses of forty to describe lengths of time need not necessarily mean that forty years passed, but rather that the time period in question (the rule of a king or judge) lasted for a generation.
* The three periods in Moses life – birth to departure from Egypt, time spent away from Egypt to the departure of Israel from Egypt, and the wilderness wanderings
* Times of peace in the era of the Judges (Judg 3:11, 5:31, 8:28, 1 Sam 4:18)
2. a time of testing, 40 days
The number forty is also used to describe a length of time (1) during which divine testing or instruction took place or (2) a length of time before a significant event:
Gen 7:4 For in seven days I will send rain on the earth for forty days and forty nights; and every living thing that I have made I will blot out from the face of the ground
Gen 7:17 The flood continued forty days on the earth; and the waters increased, and bore up the ark, and it rose high above the earth.
Gen 8:6 At the end of forty days Noah opened the window of the ark that he had made
Ex 34:28 “He was there with the Lord forty days and forty nights; he neither ate bread nor drank water. And he wrote on the tablets the words of the covenant, the ten commandments:
1 Kings 19:8 He got up, and ate and drank; then he went in the strength of that food forty days and forty nights to Horeb the mount of God.
Matt 4:1-2 Then Jesus was led up by the Spirit into the wilderness to be tempted by the devil. 2 He fasted forty days and forty nights, and afterwards he was famished
Acts 1:3 After his suffering he presented himself alive to them by many convincing proofs, appearing to them during forty days and speaking about the kingdom of God