The relation between the three foundational kinds of signs. Signs are objects, actions, or marks standing for things besides themselves as in figure 1. To the extent signs are consistent with what they are about, they are meaningful. Sensory signs are about material facts and depend on seeing, hearing, touching, smelling, and tasting.
Linguistic signs deal with all the foregoing.
Figure 2 shows how signs relate to each other in ordinary experience. What enables signs to be understood is their consistency with the material world. For instance, the sensory sign of the baby is understood because it is consistent with what a baby looks like. In the middle circle, the pointing finger shows that I directed your attention to the baby. Such an act of reference is a common motoric sign.