A monk asked, “What about when there is neither a square nor a circle?”
Chao-chu said, “Neither square nor circle.”
The monk said, “When things are like that, what about it?”
The master said, “Either square or circle.”
James Green, The Recorded Sayings of Master Joshu
referenced by Audrey Yoshiko Seo, Enso, Zen Circles of Enlightment
http://www.ams.org/featurecolumn/archive/svd.html|Geometric approach and samples
I’m currently reading John Medina’s Brain Rules (@amazon). Rule #6 Long-Term Memory recalls the case of Solomon Shereshevskii, which reminded my a lot Borges’ Funes el Memorioso, although JL regards it as a metaphor of insomnia. (I’m writing this just not to forget)