"Men are the dominant sign-using animals. Animals other than man do, of course, respond to certain things as signs of something else, but such signs do not attain the complexity and elaboration which is found in human speech, writing, art, testing devices, medical diagnosis, and signaling instruments. Science and signs are inseparably interconnected, since science both presents men with more reliable signs and embodies its results is systems of signs. Human civilization is dependent upon signs and systems of signs, and the human mind is inseparable from the functioning of signs - if indeed mentality is not to be identified with such functioning."