備梯

Qin Guli served Master Mozi for three years. His hands and feet were calloused, his face sunburned and dark. He worked his body hard in service and did not dare ask for anything. Master Mozi took pity on him and provided wine and dried meat. They retired to a great mountain, sat on soft grass to rest, and Mozi served Qin Guli. Qin Guli bowed twice and sighed. Master Mozi said: 'What do you wish?' Qin Guli bowed twice more and said: 'I venture to ask about the Way of Defense.'

Master Mozi said: You ask about defending against cloud ladders? The cloud ladder is a massive device, difficult to move. For defense, construct mobile walls with towers placed at intervals within view of each other, encircling the area. The dimensions should match the width of the attacking formation, with curtains hung within the enclosure, keeping the space compact. The standard for mobile walls: twenty chi high above the regular wall, with battlements on top, ten chi wide, with projecting bastions extending twenty chi to left and right, with the same height and width specifications as the mobile wall.