"To whom also he showed himself alive after his passion by many infallible proofs, being seen of them forty days, and speaking of the things pertaining to the kingdom of God." (Acts 1:3)
It is interesting how often the Scriptures refer to a fortyday period. There are nine different forty-day periods noted in Scripture (the phrase itself occurs seventeen times), and it may be noteworthy that forty days is 1/9 of the original (and prophetic) lunar/solar year of 360 days (note Genesis 7:11; 8:3-4; Revelation 11:2-3). Thus the total of the nine forty-day periods equals the ideal year.
The periods are as follows: the intense rainfall at the Flood (Genesis 7:12, 17); the first giving of the law (Exodus 24:18; Deuteronomy 9:9, 11); the second giving of the law (Exodus 34:28; Deuteronomy 9:18, 25); the searching of Canaan by the fearful spies (Numbers 13:25; 14:34); the defiance of Israel by Goliath (1 Samuel 17:16); Elijah's journey to Horeb (1 Kings 19:8); Jonah's reluctant preaching in Nineveh (Jonah 3:4); Christ's temptation in the wilderness (Matthew 4:2; Mark 1:13; Luke 4:2); Christ's post-resurrection ministry (Acts 1:3).
Each of these periods was a time of intense testing for one or more of God's people, except the last. The final forty-day period, encompassing Christ's ministry to His disciples after His resurrection, was a time of triumph and great blessing. He had come victoriously through the most intense time of testing that anyone could ever experience, and now He could show Himself alive eternally to His disciples and promise them the same victory. Forty days of testing, then forty days of triumph! Even a lifetime of testing is more than balanced by an eternity of blessing. "The sufferings of this present time are not worthy to be compared with the glory which shall be revealed in us" (Romans 8:18). HMM