Bamboo slips were one of China’s principal writing formats, its earliest kind of book, and, almost two thousand years old, longer lasting. Bamboo’s advantage over wood was its flexibility, imperviousness, smooth surface, and light weight. Each slip contained a narrow vertical column of several dozen characters. Their lengths conveyed rank, with royal decrees two feet high and ordinary texts less than a foot. As books required many slips, they were first laced together in small bundles (ce, 策), and then whole albums (ce, 冊), like signatures in a book. This last character—four sticks tied together—closely resembles its actual appearance. When not needed, scribes rolled bamboo books up and wrote titles on them for easier storage and retrieval. The texts on bamboo slips include subjects as disparate as philosophy, law, politics, mathematics, medicine, and cartography. Archaeological digs found the world’s first decimal multiplication calculator and such books as Sun Zi’s The Art of War and The Analects of Confucius. Bamboo slips established modern Chinese traditions such as the vertical format used for banners and door entries, books bound with laces, album leaves loosely joined together, title slips attached to scrolls, and calligraphy rolled up into handscrolls.