Sun Guoting?s Treatise on Calligraphy is divided into two volumes. It is generally understood that the first volume serves as the preface, while the second forms the treatise itself. The beginning is inscribed ?Treatise on Calligraphy, Volume One. Written by Sun Guoting of Wu Commandery,? and the end records that it was written in the third year of the Chuigong reign. The work is now held in the National Palace Museum in Taipei. Its content focuses on calligraphic experience, the principles behind the writing of the treatise, and basic approaches to learning calligraphy. It is both an elegantly written theory of calligraphy and an ideal model of cursive script. Sun Guoting studied Wang Xizhi?s cursive script deeply; his brushwork is refined and fluent, capturing its spirit and essence.