When I looked at the science of engineering and saw that it had disappeared after its ancient heritage, that its masters have perished, and that their memories are now forgotten, I worked my wits and thoughts in secrecy about philosophical shapes and figures, which could move the mind, with effort, from nothingness to being and from idleness to motion. And I arranged these shapes one by one in drawings and explained them.

Al-Muradi, The Book of Secrets in the Results of Ideas, 11th century; Translated and cited at leonardo3.net/bookofsecrets/index, 2015