From its genesis in administrative and daily writings, cursive writing has opposed classical styles and has continuously transformed Chinese calligraphy. The wild cursive that appeared between the 7th and 8th centuries is generally considered to be a peak of Chinese calligraphy as a form of personal expression. However, theorists have long neglected the fact that the notion of "writing with a single brushstroke" (yibishu 一筆書) already illustrates the desire to transform writing into a continuous momentum and thus to create an effect of an infinite gesture. Writing with a single brushstroke is, nevertheless, a decisive step in the calligraphic gesture that precedes the wild cursive. Understanding the invention of yibishu sheds light on the evolution of cursive in its historical, religious, and philosophical levels. Through the analysis of works and theoretical treatises, taking into account the archaeological discoveries, this study aims to reveal an important stage that has long remained masked in the Chinese art of writing.