The late Philip J. Davis in his 2004 essay
"A Brief Look at Mathematics and Theology,"
Humanistic Mathematics Network Journal ,
Issue 27, Article 14. Available at:
http://scholarship.claremont.edu/hmnj/vol1/iss27/14/
"In my childhood, the circle persisted as a potent magic figure
in the playtime doggerel 'Make a magic circle and sign it with a dot.'
The interested reader will find thousands of allusions to the phrase
'magic circle' on the Web."
There are fewer allusions to "magic circle" + "sign it with a dot."
One such allusion (click to enlarge) is . . .
Davis died on Pi Day .