Significance of the number 40 in the Bible


I know that the number 40 is very significant in the Bible, and that it occurs in several important Biblical accounts – including 40 days of rain while Noah was in the ark, Moses and the Israelites wandering through the desert for 40 years, Jesus spending 40 days fasting, and Jesus spending 40 days with the apostles after the Resurrection. I also assume that the recurrence of the number 40 emphasizes links among some of these Biblical accounts. But why 40? Why not 30 or 50 or some other number?

One of the students in my Confirmation class asked about this last week, and I didn’t have a good answer. I haven’t had time to research this, and I teach class again tonight. I would be very thankful if someone could point me to a good answer!


St. Augustine was pretty fond of numbers and their meanings in the bible.


Wikipedia gives a long list of instances of the number 40 in Judaism and Christianity:

In the Hebrew Bible, forty is often used for time periods, forty days or forty years, which separate “two distinct epochs”.[1]

Rain fell for “forty days and forty nights” during the Flood
Spies explored the land of Israel for “forty days.” (Numbers 13)
The Hebrew people lived in the Sinai desert for “forty years”. This period of years represents the time it takes for a new generation to arise.
Moses’ life is divided into three 40-year segments, separated by his fleeing from Egypt, and his return to lead his people out.
Several Jewish leaders and kings are said to have ruled for “forty years”, that is, a generation. (Examples: Eli, Saul, David, Solomon.)
Goliath challenged the Israelites twice a day for forty days before David defeated him.
Moses spent three consecutive periods of “forty days and forty nights” on Mount Sinai:
He went up on the seventh day of Sivan, after God gave the Torah to the Jewish people, in order to learn the Torah from God, and came down on the seventeenth day of Tammuz, when he saw the Jews worshiping the Golden Calf and broke the tablets
He went up on the eighteenth day of Tammuz to beg forgiveness for the people’s sin and came down without God’s atonement on the twenty-ninth day of Av
He went up on the first day of Elul and came down on the tenth day of Tishrei, the first Yom Kippur, with God’s atonement
A mikvah consists of 40 se’ah (approximately 200 gallons) of water
40 lashes is one of the punishments meted out by the Sanhedrin, though in actual practice only 39 lashes were administered.
One of the prerequisites for a man to study Kabbalah is that he is forty years old.

Christianity similarly uses forty to designate important time periods.[1]

Before the temptation of Christ, Jesus fasted “Forty days and forty nights” in the Judean desert.
Forty days was the period from the resurrection of Jesus to the ascension of Jesus.
In modern Christian practice, Lent consists of the 40 days preceding Easter. In much of Western Christianity, Sundays are excluded from the count; in Eastern Christianity, Sundays are included.
The Forty Martyrs of Sebaste
Kirk Kilisse, “Forty Churches” (Σαράντα Εκκλησιές) in Eastern Thrace

I would add, there were also about forty years between the death and resurrection of Christ and the destruction of Jerusalem and of the Temple. In a rough way that is, certainly not to the day even if Christ was crucified in AD 30, which is far from certain. That’s about forty years of infancy for the Church.

Anyway, these numbers mutually relate to each other, the earlier ones prefiguring the later and the later referencing the earlier. But why forty? Is there something intrinsically meaningful about the number? Christian numerology has explored such topics starting with the number three as representing the Trinity and then looking for related significance in the other numbers of the Bible, but that kind of thing can easily get far-fetched. Also there is Wikipedia’s suggestion above that forty years represents the length of time it takes for a new generation to arise. If that is the case it would seem that the forty years in the desert may be the really practical instance of the number, with the other instances through history being providentially connected to it and to each other.

In any case the number something which knits together salvation history through time.


Unfortunately, I don’t have time to read all the works of St. Augustine before I teach my class tonight. :slight_smile:

But I do appreciate the recommendation, and if I get time later I may peruse through some of his writings.


Thanks for your reply. Indeed, that is the question, “why forty?” I have done a bit of searching on and on, but I haven’t found an answer. I do like your idea of the length of time for a generation of adults to die and be replaced by a new generation, and I think something to that effect actually is mentioned in the Bible, if I recall correctly. Maybe that’s the only reason for 40 as opposed to some other number, or maybe there is more to it than that.


I find it interesting that as humans we spend an average of 40 weeks in the womb.

Just a coincidence? I doubt it.


40 indicates a time of testing.

Israel was tested in the desert for forty years. They asked for a king and God tested them with King Saul for forty years, to see how they would act, whether they would continue to follow God or if they would put all their trust in the king. Jesus was tested forty days in the desert.

There are very many other instances of the number 40 indicating that someone is being tested.

Lent is 40 days.



Where 40 measures time, I regard it as a period of preparation for something more significant.

Otherwise, in Middle Eastern cultures I believe it’s traditional shorthand for “a lot” in the way we use “a million;” e.g., Ali Baba had forty thieves.


Good insights, and I agree. But I think this still leaves the question of why 40 rather than some other number. In other words, if the Israelites had wandered the desert for 50 years, and if Jesus had been tested for 50 days in the desert, and so on, so that every instance of 40 in the Bible was replaced with 50, then we could just as well say “50 indicates a time of testing.” So I still wonder why 40 rather than 50 (or any other number)?


That’s an interesting insight, and it might be the answer I was looking for. So just as today we might say “a million” when we really mean “a lot” or “a huge number,” the people in ancient Middle Eastern cultures would have said “forty” to mean a large number, if I understand you correctly. If that is so, then I think that is a good explanation for my question. Thanks!


The Hebrew letter associated with the number forty is the letter mem, which is our letter M.
It is associated with water in ancient alphabets, including the Egyptian and the Phoenician.



The planet Venus forms a pentagram in the night sky every eight years with it returning to its original point every 40 years with a 40 day regression (some scholars believe that this ancient information was the basis for the number 40 becoming sacred to Jews, Christians, and Muslims).[citation needed]

It would not be surprising if there were some ancient astrological reason for the significance of the number 40. There certainly is the mythological connection between the planet Venus and water as well.

As an aside, the importance of twelves and sixties in astrology and geometry (cirle of 360 degrees eg). It may have arisen from something as simple as counting the number of finger segments on one hand with the thumb(4fingersx3knuckle segements=12) and keeping track of how many twelves on the other hand (5x12=60)

The ancients were stargazers though, and the significance of numbers often involves astrological events in the sky.


There does seem to be the same kind of spiritual significance with the water of the womb as jesus passing through the water of Baptism and entering into the trial of the desert for the period of 40.
Similarly birth motifs are involved in the blood on the doorways of the houses of life in Egypt that were passed over, and the Hebrews passing through those entrances like a child exiting from a bloodied birth canal. The birth motif continues with the Hebrews similarly passing through the waters of the Reed Sea into forty years of trial and purging in the desert. Miriam is intimately associated with water in these stories too by the way, hiding in the reeds waiting for the pharoahs daughter to bring Moses forth from them, singing her own special song after passage through the parted waters, and even with the waters that sustained the Hebrews in the desert for those forty years of wandering-Miriams well as it is known to Jews, and which dried up upon her death in that desert.
She is very much a prefiguration of Mary, who likewise was there initiating the beginning of Jesus’s ministry at the wedding where he turns the water into wine.
Forty is the time of formation and the trials involved in the proper formation, of the body in the womb in the one case, or of the spirit in an atmosphere of complete dependency and trust in the Lord providing in the deserts of 40 days and 40 years respectively.




This site is quite interesting because it shows how important that this type of symbolism, based on the orbital rotation of Venus in the Earths sky, played in Christian iconography

The five and eights (40) associated with this five petaled astrological rose do seem to be traceable back to Babylonian times as well, and therefore may be linked to the Biblical significance of the number 40. The time frame fits if it extends that far back in time.


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