: a proportion (such as one involving a line divided into two segments or the length and width of a rectangle and their sum) in which the ratio of the whole to the larger part is the same as the ratio of the larger part to the smaller"
It deals with a unequaled recurrent relation among “media and extreme ratio”, perpetually equal to itself in opposite directions, which virtually brings the concept of simultaneity of the movement both towards the future (×j) and towards the past (÷j).
Indeed it owns a double, irrational face; so if this is Phi:
F = 0.61803398874989484820458683436563811772030917980576…this is phi:
j = 1.61803398874989484820458683436563811772030917980576…