Basic constructions
Nigel Hiscock, in his book The Symbol at Your Door writes: “Also profuse in medieval architecture and art is the vesica piscis. Increasingly from the ninth century onwards, it was chosen to enclose Christ and certain Holy Roman emperors when seated in majesty, and in the case of Christ, usually attended by the symbols of the 4 Evangelists at the 4 corners of a page or a relief. […] The form of the vesica piscis, enclosing Christ in the overlap of two circles, sometimes represents in the East his aura of divine light[…]. In the West, the geometric figure appears to express his governance over the two circles of heaven and earth.”
Images and figures of the Blessed Virgin Mary were also enclosed in the Vesica Piscis composition and, additionally to historical, contemporary examples can be found in liturgical arts. The Vesica Piscis shape is also called the Mandorla, which in Italian means the almond nut. This geometric figure, with separate symbolisms, can be found in traditions other than Christianity. Mathematically, a Vesica Piscis is a lens, a shape formed by the intersection of two disks. There are two equilateral triangles, base to base, inside the Vesica Piscis. There are in fact many mathematical relationships within this shape, which, since I am not a mathematician, I am not equipped to explain. For those who are setting out to draw the Cosmatesque ornaments it is the divisional property of this geometric figure which will be important. It will allow for the division of a circle into 4 equal parts and a segment into 2 equal parts. Both these divisions will become invaluable. The below instructions will guide through its construction.
With this commencing drawing tutorial I would like to thank those who oversaw my first circles, mostly at the King’s Foundation School of Traditional Arts, London, where I did my Master Degree: Lisa DeLong, Simon Trethewey, Amber Khokhar, Tom Bree, Jonathan Horning and others, both tutors and fellow students. I thank you all for passing on your knowledge to me and for your companionship in the land of geometry. I hope you are glad to see me carrying on with this magnificent craft.
The Vesica Piscis division of a Circle into 4 equal parts
Materials:
compass
30cm ruler
H or 2H pencil
A4 printer paper
card or cutting mat
eraser
Notes:
place the A4 printer paper horizontally
measurements are approximate as this construction works regardless of the size of radius, feel free to adjust to your manual and visual needs
please use the contact button should you have any queries or would like to share your work
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Every Cosmatesque ornament, every geometrical construction, every quincunx or interlacing guilloché we will draw starts with a point which the compass makes in the paper and then the circle which the compass marks. Both point and circle correspond to the number one and are symbolic of the unity of being, transcending all that exist. To my simple mind, it is the symbol of God from whom all things come and to whom, one day, I hope to return.
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1) With radius approx. 4cm draw a circle in the middle of your horizontally orientated A4 page of printer paper. Mark your centre as point Z.
2) Draw a horizontal line across the circle. Allow the line to extend through the circumference of the circle on both left and right. Make sure this line accurately crosses point Z. Mark intersections A and B.
3) Place your compass needle in point A and stretch the other compass leg to point B. From point A, with radius AB, draw an arch.
4) Place the compass needle in point B and with the same radius AB mark an arch which will mirror the previous one. These two arches should cross above and below your circle. Mark intersections C and D. You should now have a Vesica Piscis enclosing your original circle.
5) Join points C and D with a vertical line. This line should go right through the middle of your circle, point Z. You should now have your circle divided into 4 equal parts. This construction also divides the segment AB into 2 equal parts.
6) You can use a set square or simply a piece of A4 paper to check the right angles between your horizontal and vertical lines.