58

O.57

that a thought fulfills this definition of a sign. All the signs used in Deduction are creations of the Mind both Utter (i.e. create and put into expression,) and Interpret (i.e. perceive the relations of signification,) of three kinds of Signs; namely, Icons, which I have already defined, such as the construction in a demonstration of Euclid, Indices, or signs which stand for the Real Objects and Facts for which they stand by virtue of being actually connected with them, such as the letters which distinguish the three angles of one of Euclid's triangles; and Symbols, or general conventional Signs, which stand for what they do because they will be so interpreted. For Deduction merely developes