I analyze the notion of sign as a referential association. I concentrate on Peirce’s tripartite system of signs, namely, indices, icons, and symbols, because Peirce was, perhaps, the first to distinguish systematically between the various kinds of signs and discus their interrelations. Peirce thought that indices are referentially more complex than icons in the sense that icons are necessary for fixing the reference of indices. I explain why I disagree with Peirce and argue that icons are a later evolutionary step in that they are representations, while indices are not, and, thus, came first. Then, I distinguish between internal, mental, representations and physical external representations, and I emphasize the distinction between the vehicle of a representation and, when it applies, the representational content of the representation, and the object of the representation. Finally, I explain why indices, in Peirce’s vocabulary, are not representations.