Platonic solid
Stevenson based his compositions on the [[golden ratio]], first referred to by [[Leonardo da Vinci]] as the "secto aurea" (golden section). Leonardo's line drawings of the [[Platonic solid|five Platonic solids]] illustrate [[Luca Pacioli]]'s book "La Divina Proportione" (1509). One of Stevenson's reference books on the subject was "Elements of Dynamic Symmetry" by [[Jay Hambidge]].