By Casey Chalk
It's easy to get lost in Biblical numerological speculation, as even a cursory study of the Church Fathers proves. St. Irenaeus attempted to explain the number of the beast from Revelation 13:17–18 by adding the numerical value of the Greek letters in the names "Evanthas," "Lateinos," and "Teitan" to get the ominous 666. St. Augustine argues that the meaning of 153 fish caught by the Apostles (John 21:11): there are Ten Commandments, the number seven signifies holiness, ten plus seven equals seventeen, and if all the numbers from 1 to 17 are added together (e.g. 1+2+3, etc.) they equal 153. St. Cyril in contrast breaks the number 153 into 100 (the large number of Gentiles to be saved), 50 (the small number of Jews to be saved) and 3 (the Trinity).
Given such seemingly unsubstantiated speculation, it's easy to be tempted to throw up one's hands and conclude that looking for spiritual significance in the various numbers of Holy Scripture is not a particularly fruitful enterprise. The writings of the church father and Doctor of the Church St. Isidore of Seville (560-636) – whose feast day we celebrated earlier this month – should, however, give us pause. His work The Mystical Meaning of Numbers in Sacred Scripture helps clarify why the use of numbers in the Bible matters in exegesis and theology.
St. Isidore was one of the most celebrated men of the seventh century. Born into a pious family (his brothers Leander and Fulgentius and sister Florentina are also saints), Isidore was in time appointed Vicar Apostolic for the whole of Spain by Pope St. Gregory the Great.
He convened a Council of the Church in Spain (the Second Council of Seville) in response to the heresy of the Acephali, which rejected the teachings of the Council of Chalcedon on the union of the divine and human natures in Christ. He also convened the Fourth Council of Toledo, which bound the Spanish monarchy to the Catholic Church and established seminaries for the formation of clergy.
Only sixteen years after his death, the Spanish Church at Toledo unanimously agreed he should be declared both a saint and a Doctor of the Church. Because of his writings on numbers, Pope St. John Paul II in 1997 declared Isidore the patron saint of the internet.
Holy Scripture teaches: "In measure, and in number, and in weight Thou hast ordered all things." (Wisdom 11:21) Inspired by this, Isidore's Etymology sees a symbolic value in numbers:
The importance of numbers should not be overlooked, and in many places in the Sacred Scriptures mystical meanings shine forth through them with radiance and illumination. . . .And if number and quantity were to be taken away from creation, all things would lose their forms and cease to exist.
In The Mystical Meaning of Numbers in Sacred Scripture, Isidore walks us through such interpretations, from numbers one through twelve.

One, for example, "represents both indivisibility and completeness," whose exemplar and archetype is God Himself, the origin of all things: "One or unity is the seed and basis of all subsequent numbers. For out of unity, all subsequent numbers emanate or are created."
Of course the most perfect example of unity is God, as the Shema asserts: "Hear, O Israel: the Lord our God, the Lord is one." (Deut. 6:4) The Church is also one, though the sins of her members undoubtedly harm that oneness, as the sins of the individual Christian harm the integrity of the wholeness of the human person created in God's image.
Two is the first number that can be divided, and thus "represents the possibility of fundamental opposition," giving rise to potential conflict: good and evil, light and darkness, life and death.
The Old Testament is filled with examples of such oppositions: Cain and Abel, Saul and David, Israel and Judah. Jesus employs it constantly in His parables: wheat and tares, sheep and goats, the two sons. Isidore's analysis also anticipates a response to Protestant thought: "There are two aspects or means which ...

St. Isidore Runs the Numbers