A propositional sign, applied by thinking it, is a thought.

The sentence determines a location in logical space. The existence of this logical location is established by the mere existence of the components, by the existence of a sentence that makes sense. The sentence and the logical coordinates together constitute a logical location. The geometric and logical location are alike in that both allow something to exist.

Although the sentence is allowed to determine only one location in logical space, nevertheless, it must already establish the whole of logical space. (Otherwise negation, logical sum, logical product, etc., would introduce more and more new elements in co-ordination.) The logical framing of an image determines its logical space, while the sentence extends through the whole of logical space.