Of great symbolic significance, a first application comes immediate, going to navigate in the coveted structure of the famous

Vitruvian Man

to discover – not less by the golden circles ex­pan­sion map – new a­maz­ing pro­por­tions re­sult­ing inside the ideal figure of the human body.

In his celebrated “De architectura” Book III, Chapter 1, Vitruvius mainly points out these proportions of the average adult body (plus many oth­ers, for who'd want to pros­e­cute):

“§3. Thus, the navel is naturally the center of the body. In fact, if a man were placed supine with his hands and feet stretched out and the center of the com­pass was put on the navel, tracing a circumference would tan­gen­tially touch the fingers and toes. But that's not all: beyond the scheme of the cir­cle, the figure of the square will also be found around the body. In deed, if we measure from the plane of the feet to the apex of the head, and then we transfer this measurement to the hands out­stretched, a length equal to the height will be found, so that distances at right angles to each other, will de­lin­e­ate a square en­clos­ing the figure…”
Upon these writings Leonardo da Vinci based his Vitruvian Man.

However, a circumference that tangentially to­uch­es the toes, to also touch the fingers re­quires, as we can see, the rotation of the arms of an arc with ra­di­us half side of that squ­are, arc ap­prox­i­mate­ly (but not rightly) centered about the cross­ing of the two lines as they were meas­ured to de­fine the square itself, suit­a­ble to re­ach the circle with the ex­ten­sion of an arm.
Here is the basic facility; but how to get the navel to draw the circle?