Part III: The Circumference and the Hieroglyphic Monad in In Operibus Sigillo Dei Aemeth by David Richard Jones.

“The encoding of this connection is indicated by the relationship of the geometry of the Monad with that of the Sigillum. Note that the problem of constructing a regular heptagon sept-dividing (dividing a circle into seven equal parts) with the aid of a compass and a straightedge only without the aid of measurement has been a problem since classical times. So difficult a problem is it that no such formulation is provided in the Elements of Euclid, to which John Dee wrote his famous preface. A solution by Archimedes is preserved in Arabic, but was not rediscovered until 1927, and is notable even to its author/preserver for its lack of elegance.” [via]