While it would require an infinite number of monkeys with an infinite number of typewriters an incredibly long time to, by chance, type out the complete works of Shakespeare, giving white paper and a set of markers to an artist, graphic designer, and author seems to more easily result in incomplete rainbows on the edges of book covers.
I can’t claim to have any real interest in rainbows. I am, however, interested in designs which are completely unrelated but share graphic elements. It seems these items must be somehow connected. They aren’t. It’s just a contrived coincidence—and that’s OK. Comparing and contrasting are essential tools for seeing and understanding what we see. For me, these three items aren’t really about rainbows. They’re simply about looking closely and making connections.