An ancient Chinese calligraphic script developed during the Han dynasty (206 BC to 200 CE) and widely adopted for official and educational purposes. It developed from seal script (zhuanshu), originating in the brush writing of the later Zhou and Qin dynasties. It first appeared in the Qin Dynasty (221-226 BCE), and came into its mature form during the Eastern Han dynasty (late 3rd century BCE). Though somewhat square and angular, with strong emphasis on the horizontal strokes, the lishu is a truly calligraphic script type, making full use of the flexible brush to modulate the thickness of the line. Many Han examples survive, written with a brush on bamboo slips or carved in stone. Characters were approximately uniform in size and evenly spaced within a composition, but the construction of characters and individual strokes varied greatly. The main characteristics of the clerical script are its angular strokes, which replaced the rounded lines in the seal script, and its simplified character structures, which defied the six principles of Chinese characters. Clerical script laid the foundation for the development of later scripts, including the standard or regular script, the running or semi-cursive script, and the cursive script. A prisoner Cheng Miao is said to have created this script, and the new style of writing became popular among prison workers for clerical documents and transcriptions. At the end of the Han dynasty the lishu developed into the more supple and fluent kaishu.
