ABSTRACT
We turn now to our central task, that of specifying the essential features of signs of differing levels of complexity. We begin with the simplest level, that of natural signs as objects or events in the environment of their interpreter which are not produced by some agent with the intent to communicate. Our historical sketch has shown a great variety of signs to have been classified under this heading, including the classical evidential signs, material images, and sensations. We now look more critically at these classifications with an eye towards developing a conception of a natural sign for which important analogies to linguistic signs hold. We thus consider evidential signs in the first section of this chapter and images, both material and sensory, in the second. In the final two sections are outlined the essential features of a severely restricted range of signs that we label 'natsigns' and distinguish from the natural signs of the tradition.
