A bishop who loved arithmetic
Augustine of Hippo, who lived from 354 to 430 in what is now Algeria, wrote more about number than almost any other writer of the early Latin church. His interest was not in predicting anything. It came from a conviction about creation: that the world is ordered, that order is intelligible, and that number is among the clearest signs of that intelligibility.
His reading of numbers in the Bible was one expression of this conviction. The wider survey of how churchmen treated such numbers belongs to Christian number symbolism; this article stays with Augustine’s own reasoning.
Measure, number and weight
A key text for Augustine was a line in the Book of Wisdom saying that God arranged all things in measure, number and weight. He quoted it often, and it let him join two traditions: the biblical story of a made world and the philosophical idea that number lies behind form. He had absorbed the second from Platonist writers, who were in turn heirs of the Pythagorean number philosophy.
For Augustine the argument ran roughly as follows. Things have shape, proportion and sequence. Proportion and sequence are matters of number. Numbers themselves are not made by human minds, since two and two make four whether or not anyone thinks about it. They are therefore best understood as part of the order that God established, which the human mind can recognise but not invent. In his dialogue on free will, he used the stability of numbers as a pointer to truths that are not produced by individual people.
This is philosophy, and readers may or may not find it persuasive. It should be read as Augustine’s argument and not a demonstrated claim about the world.
Number in music and learning
Augustine also wrote a work on music, which is largely about rhythm and proportion, in which he treated the ratios behind a regular beat as examples of numerical order in sound. In his autobiography he described his own early studies, including mathematics, and later he argued that the liberal arts could train the mind to move from changing things to unchanging ones.
His position was that mathematical study is useful as a ladder, not as an end. A person who admired the order of numbers but stopped there, in his view, had missed the point.
The number of the days of creation
The best-known application of this thinking was to the six days of creation. In the City of God and elsewhere, Augustine drew on a long tradition that called six a perfect number, in the sense that it equals the sum of its divisors other than itself: 1 + 2 + 3 = 6. That is arithmetic and is true; the perfect number six is also discussed in the Greek mathematical tradition.
Augustine’s twist was to say that six is perfect in itself, whether or not anything had been created, and that the work of creation was set out in six stages because that number suits completeness. He added that the creation account may not describe ordinary days at all, and he was cautious about claiming to know exactly how the days should be understood. The seven-day structure of Genesis, with its day of rest, had its own meaning for him as a picture of completion.
The 153 fish
One famous example is in the Gospel of John, where a catch of 153 fish is recorded after the resurrection. Augustine, like some other early writers, thought the number had to mean something. He noted that 153 is the sum of all the whole numbers from 1 to 17, which is correct: 17 × 18 ÷ 2 = 153. Triangular numbers of this kind were well known to ancient arithmeticians.
He then offered a reading. In his interpretation, ten could stand for the law, given as ten commandments, and seven for the Spirit, since Scripture speaks of the sevenfold gifts of the Spirit. Together they make seventeen, and the sum of the numbers up to seventeen is 153. His point was that the catch represented a whole community drawn from many peoples and brought into the faith, under both law and grace.
Not every reader found this convincing, then or now, and Augustine did not claim it was the only possible interpretation. He offered it as one fitting reading among others.
Forty and other figures
Augustine also commented on forty, the number of days of Lent in later practice and the length of the fasts of Moses, Elijah and Jesus in the Bible. He and other writers also noted that forty is four times ten, and read it as a number tied to a period of discipline or trial. The wider theme of the number forty in Scripture has its own history; Augustine is simply one of its early interpreters.
A rule for reading
What makes Augustine more than a collector of curiosities is that he also set limits. In his work on Christian teaching, he argued that readers need to know the meaning of numbers in order to understand some figurative passages. At the same time, he insisted that the plain meaning of a passage should not be thrown aside, and that figurative readings should fit the faith of the church.
He also admitted that many numbers in the Bible were beyond him. That honesty is part of the reason later writers cited him so often, sometimes more confidently than he had written.
Legacy
Medieval commentators treated Augustine as an authority on number readings, and phrases from his works recur in later discussion. His idea that the order of number reflects divine order also shaped later thinking about architecture, music and poetry. It was echoed centuries later in the carefully counted design of Dante’s Divine Comedy.