If the new arrangement of the old signs were nothing but a new symbol it would not symbolize anything before a new signification had been given to it by a special definition; but an expression expresses its own meaning, it cannot be given a meaning post festum. Let us illustrate the difference by an example. If I know that the sign Ⅿ stands for a certain sound, we have to do with a mere representation, and therefore the same sign turned upside down ꟽ will have no signification until someone has explained to us that, by arbitrary convention, it shall represent a certain other sound (double-u) ; so in this case we have only formed a new sign out of an old one.
Now let us take an example of a real Expression. If we understand the meaning of the proposition “the ring is lying on the book”, and if we rearrange the parts of it so as to form the sentence “the book is lying on the ring”, we understand the meaning of the second proposition immediately, without explanation. We do not have to wait till a meaning is assigned to it, the meaning is determined by the sentence itself. If we know which state of affairs is described by the first proposition, we necessarily know also which fact is described by the second one; there is no doubt or ambiguity. Let us repeat: the signification of a simple symbol (a name) has to be explained separately, the meaning of an expression (a proposition) explains itself, if only the vocabulary and the grammar of the language are known.
5. Structure and material.
Thus far we have found that the possibility of expression seems to depend on the possibility of arranging signs in different ways, in other words, that the essential feature of expression is Order. Speech is based on a temporal order of signs, writing on a spatial order. When we read a written sentence aloud its spatial order is translated into the temporal order of the spoken sentence. The possibility of such a translation proves that the particular spatial or temporal character of different languages is not relevant for the expression; the order which is essential for it must be of a more general or abstract kind, it must be something that belongs to speech just as well as to writing, or indeed to any other kind of language. It is not spatial order that is required, nor temporal order, nor any other particular
