There is a progression from pictographic, writing the picture; to ideographic, writing the idea; and then logographic, writing the word. Chinese script began this transition between 4,500 and 8,000 years ago: signs that began as pictures came to represent meaningful units of sound. Because the basic unit was the word, thousands of distinct symbols were required. This is efficient in one way, inefficient in another. Chinese unifies an array of distinct spoken languages: people who cannot speak to one another can write to one another. It employs at least fifty thousand symbols, about six thousand commonly used and known to most literate Chinese. In swift diagrammatic strokes they encode multidimensional semantic relationships. One device is simple repetition: tree + tree + tree = forest; more abstractly, sun + moon = brightness and east + east = everywhere. The process of compounding creates surprises: grain + knife = profit; hand + eye = look.