Cai Lun

Cai Lun the Chinese eunuch official of the Eastern Han dynasty (c. 50-121 AD) who is credited by tradition with the invention of paper and with presenting it to the emperor in 105 AD. His improvement of the writing material transformed the transmission of knowledge in China and eventually throughout the world.

Early Life and Career at Court

Cai Lun was born around 50 AD, in the region of Guiyang in present-day Hunan, and he entered the imperial palace as a eunuch during the reign of Emperor Ming. He served the court for many years in positions of trust, and he rose to become a senior official in charge of the workshops and of the imperial manufactories.

His duties brought him into close contact with the production of goods for the court, and he had charge of the workshops that made instruments, weapons and other articles for imperial use. This administrative experience gave him oversight of craftsmen and materials, and it was from this position that he turned his attention to the problem of writing supports.

He was trusted by the emperors he served and was known for his diligence and his loyalty. He became involved, however, in the factional struggles of the court, and his association with the empress and the politics of the inner palace would eventually contribute to the circumstances of his death.

The Invention of Paper

Before the invention attributed to Cai Lun, the Chinese wrote on a variety of materials. They used strips of bamboo and wood, which were heavy and bulky, and they used silk and, in a limited way, coarse fabrics, which were expensive. Bamboo books filled many rolls and were awkward to store and carry, while silk was beyond the means of most people.

According to the account in the dynastic history, Cai Lun in 105 AD made a paper from the bark of trees, hemp waste, old rags and worn fishing nets. He beat these materials into a pulp, spread it on a screen to drain and to dry, and produced sheets that were light, smooth, inexpensive and suited to writing. He presented his paper to Emperor He, who praised it, and its use spread rapidly.

The story that Cai Lun is the sole inventor of paper is a simplification, for archaeological finds have shown that a rough paper existed in China before his time. His lasting achievement was to improve the process, to standardise the materials and to make paper a practical and widely available medium. It is for this improvement and for its adoption by the court that tradition honours him.

Manufacture and Materials

The paper of Cai Lun was made from a variety of fibrous materials, and this was the secret of its success. The bark of the mulberry and other trees supplied long fibres, while rags of hemp and linen, worn fishing nets and waste from textile production provided recycled fibre. By combining these sources he made use of cheap and abundant materials that would otherwise be discarded.

The process involved soaking and beating the raw materials into a watery pulp, then lifting a thin layer of the pulp on a mould with a screen, pressing out the water and drying the sheet. The result was a material that could be produced in large quantities and that held ink well. It could be made in different sizes and weights for different purposes, and its manufacture could be carried on wherever the raw materials were found.

The making of paper required only simple tools and modest skill, and it spread quickly through the provinces of China. Over the following centuries workshops multiplied, and paper displaced bamboo, wood and silk as the ordinary medium of writing and record-keeping, an advantage that reached into every corner of administration, scholarship and commerce.

Spread and Global Influence

Paper remained a Chinese speciality for centuries. Its manufacture spread to Korea and Japan, where it was adapted and refined, and it reached the Islamic world when papermakers were taken from Central Asia after the Battle of Talas in 751 AD. From the Islamic lands the technique passed to the Mediterranean, and from there to Europe, where it arrived in the medieval period.

The arrival of paper in Europe transformed the conditions of learning. It was cheaper and more abundant than parchment, and it made possible the multiplication of books that preceded and accompanied the invention of printing. When movable type was developed in Europe in the fifteenth century, paper supplied the material that made large editions practical, and knowledge began to circulate on a scale never before seen.

The chain of transmission that begins with the workshops of the Han court thus runs through the whole history of the book. It is difficult to imagine the spread of literacy, of religion, of science and of literature in the world without the humble material that Cai Lun and his craftsmen made available, and his name has become inseparable from the invention of paper.

Death and Legacy

Cai Lun's later years were clouded by palace intrigue. He had long been associated with Empress Deng and with the imperial household, and after the death of an empress whose cause he had once served, he was summoned to answer for his earlier involvement in court affairs. Facing the prospect of disgrace and punishment, he is said to have taken his own life in 121 AD.

His invention outlived the troubles of his career and became one of the most important technologies in human history. In later ages he was honoured as the patron of papermakers and of stationers, and temples were dedicated to him by those whose livelihood depended on his craft. His name became a byword for the craft of making paper.

He is remembered as a figure whose practical genius opened the way to the world of the written page. Whether or not he was the first to make paper, it was he who gave it a usable form and the patronage of the court, and the consequences of that act have shaped the communication of knowledge for nearly two thousand years.

See also

• Paper
• History of paper
• Printing
• Han dynasty