15 - Kathleen O’Brien

The Art 


“Pentad” by Kathleen O’Brien, 
watercolour, drawing, collage, 12 x 7.5, collage on Arches Cover;
From the series “The Mystery of Numbers”,
abstract watercolors, drawings, ephemera from an antique encyclopedia and Forget-Me-Nots.


Kathleen O’Brien writes…

“Pentad”, from this series of Golden Rectangles, revisits one of my favorite subjects, Sacred Geometry, the development of numbers and related forms starting with one. The flatness of the basic forms are well suited to the flatness of collage. The method of construction of Pentad or Pentagram is complicated and was kept secret until Luca Pacioli (da Vinci’s teacher) published Divina proportione in 1509. 

First one must create the Dyad from intersecting circles which creates the shared space, the vesica piscis. Next, once creates the Triad and triangle, then Tetrad and square. Using the points of the 4 previous forms one can draw the Pentad. Its geometry is seen often in nature, like the seeds of the apple, a starfish, and our own hands.

The Music

The Phi of Five

Helen Davey

"The Phi of five" (for 5 voices, frame drum, shaker, lap harp and hackbrett) is a sound-painting in response to an artwork called "Pentad" by Kathleen O'Brien. More info about this cross arts project here: https://helendavey.com/blog/week-15-kathleen-obriens-pentad/
Read more…


Focussing on the mountains in Kathleen’s artwork, “The phi of five” is a meditative pathway on five-ness. The meter is set in 5/4;  I have used a hackbrett (Swiss hammered dulcimer) tuned to a C pentatonic (5-note) scale;  the harmonic structure emphasises the consonance of the perfect 5th, unison/tonic and the octave (in equal temperament rather than Pythagorean or vedic tuning) which are all paramount in the first 5 notes of the overtone/harmonic series;

I’ve also used the first 5 numbers of the fibonacci sequence when the fundamental tone is C (as this diagram of piano keys indicates). At the time when Pacioli revealed the golden ratio in his “Divina Proportion”, people believed that the world was flat and a firm dome – the firmament – separated the earthly waters from those above.

As a “forget-me-not” to this time period, I took some Latin text from Hildegard von Bingen* where she describes the firmament. I’ve also referred to some of the key mathematicians who contributed to the development of the golden ratio (from Pythagoras ca. 490 – 430 BC) through to Paciolli (1445 – 1517). 

For a person who finds it difficult to remember their own telephone number, researching the topic of sacred geometry was fascinating for me!

Sending you a high 5 and a Phi Pho Phip  
(which is phi squared when A and B are vying for 5th in line for a Pho)