To determine whether someone has heard a sentence, they can be asked to repeat it or write it down. The fact that they can write down the sentence they hear to show that sentences are fairly abstract, being invariant across both users and sense modalities. However, the utterance and inscription are normally much more concrete than the sentence itself, and between these and the sentence there are intermediate levels of abstraction belonging to phonology and orthography. But sentences should be focused because it is to them that meaning primarily attaches.