To me the symbolism is quite clear, but admittedly that is probably something to do with my years spent in Esoteric circles.
The Spiral of Time is a very ancient belief which has mirrors throughout Freemasonry, Knights Templar, Golden Dawn
et al traditions.
If we consider ITLAD/CTF to be about Subjective consciousness, that being YOU - the individual, then we each have our spiral of time, existing in concentric circles almost to infinity, but not quite. In CtCw I talk of Consciousness Fields, or seas to continue the Bucket and Sea analogy. In this sea exists all our individual spirals, like droplets in a vast ocean, each creating its own ripples, interracting with others but ultimately finite.
The spiral is a beautiful example of how pure Mathematics is, for the Golden Ratio, Phi and Fibonnacci sequence all help to describe perfect arcs and spirals which is one of the reasons that Esoteric Philosophy and Mathematics/Geometry are so intrinsically linked.