The Unit Circle

It unfurls itself along the x-axis with a contained passion, fluctuating between -1 and 1 like a photon whose brightness is one of an infinite number of dimensionless values, coherent, distinguishable, continuous. It is counterintuitively optimistic; it insists that half of a pie should be called pi radians. It confuses to enlighten; it sends our minds rolling through loops, performing flips and inversions until we step backward and see a straight line.