Paper is considered one of the most significant inventions in history, not only because it revolutionised imperial China at the beginning of the 2nd century AD but also for its impact on technological development and the preservation of knowledge in the centuries to come.

At that time, China was a vibrant and advanced society, with an imperial court that highly valued efficient administration and written records. The bureaucracy depended on written documents to govern a vast territory, making writing materials of vital importance. Silk and bamboo were the main writing materials, although each presented significant drawbacks in terms of cost and practicality.

Cai Lun, who invented paper, was born around the year 50 in Guiyang, a province in China. From a young age, he prepared to become part of the imperial court, although the cost was high: aspiring officials of the emperor had to undergo mandatory castration. Cai Lun decided to undergo the procedure and, in the year 77, before turning 30, he was accepted as an imperial eunuch in the court. He soon stood out for his creativity, artisanal skills, and capacity for weapon design.

Some time later, concerned that the writing materials used in the court—silk and bamboo—were heavy, expensive, and difficult to produce, the emperor tasked Cai Lun with investigating how to make these materials lighter, more accessible, and cheaper.

After conducting numerous tests, Cai Lun managed to design a much simpler and more effective paper manufacturing process. This process involved macerating plant materials such as tree bark and hemp in water, sometimes even using dry rags and fishing nets. Once the pulp was formed, it was spread on a flat mould made of bamboo. When it dried, this thin layer became a durable and uniform sheet of paper.

The innovation was in the combination of materials and the production method. Unlike its predecessors, Cai Lun's paper was economical, light, and easy to produce in large quantities. The discovery was received with enthusiasm in the imperial court. In a short time, paper manufacturing spread to all cities of the Asian giant.

Multifaceted Impact

The Chinese government managed to keep the secret of Cai Lun's formula for more than five centuries until, in the year 751, after the Battle of Talas, the Caliphate of Baghdad took some Chinese artisans prisoner and forced them to produce paper in a factory in Samarkand, the first outside China.

Subsequently, paper production spread throughout the Islamic world, reaching Muslim Spain in the 12th century and then Italy, France, and other European countries by the 13th century.

Paper presented several advantages compared to previous writing materials. Papyrus, used in Egypt, was fragile and difficult to produce outside its region of origin. Parchment, although durable, was extremely expensive due to the use of animal skin. Paper, on the other hand, was cheap, light, and easy to manufacture anywhere with access to plant materials.

This long journey of Cai Lun's invention laid the foundations for a revolution in the preservation and transmission of knowledge that would transform the world. In subsequent centuries, paper became the fundamental medium for scientific and technological development. Its mass production, facilitated by Gutenberg's invention of the printing press in the 15th century, allowed an unprecedented dissemination of ideas and discoveries.

The impact of paper on technology has been multifaceted. It enabled the development of detailed plans for machines and buildings, boosting engineering and architecture. In the scientific field, laboratory notebooks and academic publications accelerated the exchange of knowledge and collaboration among researchers. It favoured cartography; by enabling the production of detailed and accurate maps, it facilitated navigation, trade, and exploration. The availability of paper allowed scientists like Al-Khwarizmi and Copernicus to widely disseminate their works, which were fundamental to the development of modern mathematics and astronomy.

The mass production of books and notebooks revolutionised education; the proliferation of textbooks facilitated the learning of various disciplines and helped educate large segments of the population. Furthermore, paper was crucial in the evolution of communication technologies. From postal mail to the first newspapers, this material laid the foundations for the creation of information networks that, centuries later, would culminate in the digital age.

A Transcendental Legacy

In the year 121, the death of the last emperor of the Han dynasty produced serious succession disputes. Cai Lun was imprisoned along with other members of the court, but he could not withstand the humiliation and decided to take his own life by ingesting poison.

His legacy, however, transcended his time. Paper, born from the practical needs of an imperial government, became the foundation for the global dissemination of knowledge.

From medieval manuscripts to printed books of the modern era, Cai Lun's invention has been fundamental in the advancement of civilisation. It not only transformed the way we preserve and share information but also paved the way for the innovations that define our modern era.