Collage by Simeon B. Mihaylov
Collage by Simeon B. Mihaylov

Deciphering Medieval Architecture

Arithmetic of the Divine

Prejudiced by Renaissance intellectuals, we often think of medieval times as an embarrassing interlude between classical times and the rest of history. The Roman empire in ruins, Europe engulfed in conflict, the roads were no longer safe for travel during the Middle Ages. Money was poured into war, not art or education. New kingdoms rose as quickly as they fell and there was little opportunity for artists to find patronage. Christianity had secured its grip on the continent and had put an end to the ‘pagan’ traditions of classical art.

Yet for all that was lost during the ‘Dark Ages’, it is a historical injustice to call them dark. The period had its own great artists and thinkers. The patronage of the Church attracted these gifted individuals and directed their work towards a common purpose. All streams of thought and art were collected in the vast ocean of the ‘kingdom of Christ on earth’.

The imperative to ‘build the Church of Christ’ was accompanied by the literal building of churches, difficult projects which preoccupied whole towns and villages. The period called for a new kind of architecture to give form to the kingdom of God.

This new architecture needed to find ‘figures, forms and symbols for invisible and incorporeal things […] for the sake of a faint understanding of God […]’ (Pro sacris Imaginibus Orationes tres). Christian scholars found those ‘figures, forms, and symbols’ in two key strands of ancient philosophy: arithmetic and geometry.

15th-century geometricians

The root ares means power and rithmus means number. Arithmetic studies the power of numbers.

In ancient Greece, Pythagoras and his followers discovered that musical harmony obeys mathematical ratios. This laid the groundwork for a new understanding of the universe as a system of mathematical laws, proportions, and axioms.

In the eyes of the Pythagorean and Platonist schools, number was not just a measuring tool, it was the fundamental language of the Universe. It was divine.

Medieval Christian scholars seized arithmetic as the perfect opportunity to make use of classical wisdom without the need to adopt any of its ‘blasphemous paganism’. They adopted the ancient Greek philosophy of numbers and saturated Christian theology with it. This gave birth to the Christian Platonist view which was to become a cornerstone of medieval architecture.

Here are some examples of how numbers were appropriated by Christian Platonists:

  • One – The number of the Monad, the one God.
  • Two – The original departure from unity, stands for discord, conflict. Two is composed of two digits (1+1), it has a beginning and an end, but no middle; therefore, it is not a ‘whole’ number. As such, it was associated with women, whom medieval scholars disliked.
  • Three – The first whole number with a beginning, middle, and end (1 + 1 + 1). As such, it stands for men, whom medieval scholars disliked less than women. Three also stands for the Holy Trinity.
  • Four – The first number that is wholly even as its middle can be divided into two (1 + 2 + 1 = (1 + 1) + (1 + 1)). As such, four stands for stability and justice. It also stands for wholeness as in the four corners of the earth, the four seasons, the four rivers that irrigate heaven, the four elements, etc. 
  • Five – Stands for marriage as the sum of the number of the female with that of the male (2 + 3). Also the number of the human microcosm (with our five senses).
  • Six – The product of the first male and female numbers (3 x 2); therefore, the number of creation. Also, the first perfect number as it equals the sum of its parts (1 x 2 x 3 = 1 + 2 + 3).
  • Seven – The virgin number. It is neither the product nor factor of any other of numbers up to ten. Represents the Holy Spirit.

 And so on…

In monastery schools, architects were educated in the liberal arts following the Greek model. The symbolism behind numbers formed a key part of the curriculum. Arithmetic provided them with a way to subliminally incorporate ideas from the Bible into their buildings.

‘Let the church be as follows: let it have three entrances for […] the Trinity […] Within the front court let there be a baptisterion twenty-one cubits in length, for […] the complete number of prophets. Let the breath [be] twelve cubits for [the apostles]’

Testamentum Domini, 5th century AD

Medieval architecture uses geometry for the same purpose.

The different polyhedrons embody different elements. Tetrahedron-fire, cube-earth, octahedron-air, icosahedron-water.

In Plato’s view, the fundamental polyhedrons represent the fundamental makeup of the universe (image above). Christian Platonists adopted a similar symbolism in which the cube became the figure for the earthly realm, and the sphere, that for the divine realm.

A church was expected to be an image of the world. (An ancient archetype I have written more about here.) Therefore, the body of the church was conceived as a cube domed by a sphere, the two shapes representing the earthly realm and the divine one above it.

This geometry worked in conjunction with the frescoes which decorated the church. It is no coincidence that images of Christ or God often appear on the central dome of churches:

‘On the very ceiling is painted in coloured mosaic cubes a man-like figure bearing the traits of Christ. Thou mightest say He is overseeing the earth, and devising its orderly arrangement and government […]’

Interior of the Florence Cathedral. The divine realm depicted on the dome. The geometry of the dome is derived from the sphere, the platonic symbol for heaven.

The church was not conceived as a static monument but as a multisensory experience. A missionary device meant to make believers out of nonbelievers. Using a combination of frescoes, arithmetic, geometry, lighting, and acoustics, churches were aiming to leave their visitors contemplating:

‘I am crucified with Christ: nevertheless, I live; yet not I, but Christ liveth in me’

Galatians II.20


‘He became man in order that we might become God.’

De Incarnatione

Total religious experience was based on the dissolution of the boundaries between the self, Christ, the Church, and the world. These elements were interlocked in a fractal-like structure where every part contains every other within itself.

Indeed, the two most widely-spread medieval church types were based on this mystical double vision through which the Church was duplicated as Christ and Christ as the Church.

The cruciform church and the round church were the two most popular kinds of medieval churches.

The cruciform church plan is a clear allusion to Christ’s crucified body. The circular church plan, the second most popular layout in the Middle Ages, represents Christ’s resurrection. Like a mandala, the circular church manifests wholeness, the completion of Christ’s work on earth, the triumph of his hero’s journey.

The church became the body of Christ. Stepping into one of those medieval temples, worshipers were entering into communion with Christ, partaking in His suffering which was at the same time the suffering of every individual. We find the seeds of this architectural symbolism in the very Gospels:

‘Jesus […] said unto them, Destroy this temple, and in three days I will raise it up.

Then said the Jews, Forty and six years was this temple in building, and wilt thou rear it up in three days?

But he spake of the temple of his body.’

John II: 19-21

This connection between body and temple has its origin in ancient sacrificial traditions and you can read my article on it here. It is interesting to consider how much of Christ’s crucifixion can be seen as an echo of ancient sacrificial rituals. The fact that this question can be approached from an architectural viewpoint is impressive by itself!

The cultural and intellectual life of Europe did not simply disappear during the Middle Ages. Like the sacking of some ancient temple’s marble for the erection of a basilica, medieval theologians scavenged ancient philosophy for the project of building Christian thought. For about five centuries, the entirety of Europe’s cultural life served a common purpose. For all that was sacrificed in this obsessive pursuit, it also yielded a synergy of spiritual, intellectual, and artistic endeavour that is rare in history.

If anything, the ‘Dark Ages’ were a time when Europe was seeking most fervently after the ‘light of God’. If one looks at the illuminated manuscripts of those times, one would find light present, and abundantly so.

To find out more about the curious symbology behind medieval architecture, you could turn to Nigel Hiscock’s monograph The Symbol at Your Door. His book, which served as the basis for this article, provides an in-depth study of the subject matter.