Early visual language systems, including cuneiform, hieroglyphics, and written Chinese, contained a built-in complexity. In each, pictographs had become rebus writing, ideographs, logograms, or even a syllabary. But these early writing systems remained unwieldy and required long, hard study to master. For centuries, the number of individuals who gained literacy was small. Their access to knowledge enabled them to acquire great power in the early cultures. The subsequent invention of the alphabet (a word derived from the first two letters of the Greek alphabet, alpha and beta) was a major step forward in human communications. An alphabet is a set of visual symbols or characters used to represent the elementary sounds of a spoken language. They can be connected and combined to make visual configurations signifying sounds, syllables, and words uttered by the human mouth. The hundreds of signs and symbols required by cuneiform and hieroglyphics were eventually replaced by twenty or thirty easily learned elementary signs. Numerous and often conflicting theories have been advanced about the origins of the alphabet; suggested sources include cuneiform, hieroglyphs, prehistoric geometric signs, and early Cretan pictographs.