Wednesday, January 29, 2014

Vesica piscis

Masonry is so full of tradition and long established practice that many of its features are taken for granted or hardly noticed.  One such feature is the common form of a pointed gothic arch, ubiquitous throughout gothic structures: as familiar as a brick wall.  This seemingly unremarkable form is actually worthy of a few remarks, so today I’ll talk about the vesica piscis.

The vesica piscis, or fish’s bladder (Latin: bladder of fish) is a geometric construction derived from two circles of the same size that overlap each other by the distance of their radius.  This shape is said to be in the form of –you guessed it- a fish’s bladder.  It is also said to be in the shape of an eye, or a vagina, or an almond.  It is said to be a representation of common understanding; the overlapping area of two different circles being the common or shared area between them. 

This shape has been imbued with deep meaning since medieval times (even earlier) and is still found in its mystical context today by freemasons who use this form in their seals and in the collars of the freemasons’ ritualistic dress.  It is said to represent the joining of god and goddess to create offspring, or a symbol of Christ himself.  In several depictions of medieval art, Christ is pictured within the vesica piscis, and is said to be Christ within the womb or vagina of the virgin Mary.  It is also said to be the shape of the wound Jesus suffered at his crucifixion.  It is taken to represent an aureole, or radiant light around the head or body of a sacred person.   It can be the basic motif in the flower of life, or an overlay of the tree of life.  It can also be used to show the formative power of polygons, or a geometrical description of square roots and harmonic proportions, or simply a source of immense power or energy.

Many of the interpretations described above are wholly embraced by the New Age movement and those who ascribe to sacred geometry.   This blog and my work are not about sacred geometry, so instead we’ll take a closer look at what the vesica piscis means in terms of masonry.

Before the advent of gothic architecture, the Roman vault or arch dominated much of European and Mediterranean masonry architecture.  This rounded arch form required much thicker walls below the arch to provide adequate support to resolve the thrusting forces resulting from the round arch, as demonstrated in analysis of catenary thrust force lines, as discussed several times on this blog.

The form created by the vesica piscis is closer to a true catenary than a semi-circular (round) arch.  This means that the arch itself and the walls upon which it rests can be made much thinner, requiring less material and less work to build.  This form still uses round segments, so it was a ‘partial’ shift away from the true round arch, and was readily accepted and adopted by architects, masons, and (perhaps most importantly) the church: whose cathedrals were built using this form.  The pointed arch is aesthetically pleasing, being close to an equilateral triangle.  It also seems to point to heaven and to God, so that one’s experience in a church can be ‘closer to God.’   Finally, we recall (as discussed several times earlier on this blog) that all masonry structures are scaleable.  This means that the vesica piscis can be made any size, as long as the proportions remain intact.  Thus this architectural motif is found throughout gothic structures, of all different sizes and scales, from small entry arches and alcoves to main structural arches and great halls.

Since my own masonry system can be used to build cylindrical sections, it can be used to build gothic arches or the vesica piscis.  I have used the vesica piscis in some of my own buildings, as entryways and as reinforcing arches above windows and doors.  It is a form which we are used to seeing; it is familiar and evokes tradition, comfort, and regularity.  Or, if you prefer, it can be a vagina, or aureole, or a fish’s bladder, or…


  1. Keep being weird. We need it. Have you applications with the steel rope interlaced as described? Keep on keeping on.

    1. Hi Douglas,
      I've made small scale models with cables. Currently I'm working on full scale block using rebar (steel reinforcement bar). I should be able to share results by fall, 2014.