Recent archeological discoveries of bamboo slips (木簡, mokkan) prove that reisho (隷書, clerical script, also known as official script) began to emerge during the Warring States period (戰國時代, 475 – 221 B.C.), long before the unification of China in 221 B.C. under the Qin dynasty (秦朝, 221 to 206 B.C.).
During the later years of the Warring States, together with increasing speed of communication, the need for a writing system that would be easier and faster than seal script (篆書, tensho), and, on the other hand, the appearance of more accessible writing tools (such as invention of paper around mid-3rd century B.C.) further encouraged the development of clerical script. By simplifying the complex structure of characters, merging dots into single lines, etc, reisho was brought to life.
One of the explanations given by historian for its peculiar name (隷, “rei” in Japanese means a “slave”, but also a “petty official”) is that it was initially used by lower class clerks, servants, etc., and the fact that it was secondary to seal script.
There is a theory that the creator of clerical script was Cheng Miao (程邈) from the 3rd century B.C., who was locked in prison for offending the despotic emperor Qin Shi Huang (秦始皇, the same one that initiated unification of great seal script under small seal script in 221 B.C.). It is said that the ten years that Cheng Miao modified the 3000 small seal script characters into reisho, also led to his release as a reward, and his immediate promotion to a high rank official of the imperial court. Recent archeological excavations however prove that reisho, like other core scripts, was not an invention of one person.
There are few types of clerical script, although two of them are the most significant. One is called korei (古隷, lit. “old slave (script)” and the other happun rei (八分隷lit. “eight parts slave (script)”).
Korei is the original form of clerical script, which differs quite significantly in its appearance from small seal script, being a blend of seal script elements with curious innovations, such as extended sweep strokes (磔, taku). In other words it was a prototype of later forms of official script.
Matured reisho in the form of happun rei (八分隷) takes its name from the shape of the Chinese character 八(hachi, in Japanese, meaning “eight”). Gradually, characters became more balanced and lines were written in a softer and more orderly fashion, eventually arriving at the symmetrically left-right divided character structure sloping like the lines of the kanji 八.
During the Eastern Han dynasty (東漢, 25 C.E. - 220 C.E.) the evolution of reisho reached its peak. There were many reasons for this. One of them was the introduction of paper and higher quality brushes, which enabled calligraphers to practice their craft with greater convenience. Another was the growing popularity of engraving texts on rocks or stalae (inscribed stone slabs), raised in memory of people or events.
Official script aesthetically differs greatly from its predecessor – the seal script. Characters are not oblong, but rather squat, and of a much more abstract form (less pictographic). Lines are of various thicknesses and the deviation from the symmetry of small seal script is very visible, too. Curves change into strokes written at steeper angles, giving clerical script a more “modern” appearance.