In linguistics, the rebus principle is the use of existing symbols, such as pictograms, purely for their sounds regardless of their meaning, to represent new words. Many ancient writing systems used the rebus principle to represent abstract words, which otherwise would be hard to represent with pictograms. An example that illustrates the Rebus principle is the representation of the sentence "I can see you" by using the pictographs of "eye—can—sea—ewe".