Time proceeds as if walking down an endless spiral.
 Twenty-four hours constitute one day, seven days one week, four weeks one month, twelve months one year. Time is divided by human beings with all these units we've invented. Though time moves forward along a straight line, it is these units that bend the line into a spiral, creating an illusion of circularity.
 “Spiral” is a clock that consists of four spirals of different revolutions, respectively representing day, week, month, and year. Moving subtly and infinitely, it resembles time passing by.