Speech consists of sounds, and writing of visible marks on a surface, and so both are concrete and exist in the material world. But the sounds of speech and the marks of writing are not language itself. Language is abstract or immaterial, something we learned as small children by listening to other people using it, not by being taught. All children, at some stage, say things like,
I’ve drinked my milk all up;
He had his foot bended like this;
He’s drawed on the window ledge;
I put a pillow that way and then sleeped on it;
all authentic recordings of a five-year-old girl. She did not learn
drinked, bended, drawed and
sleeped from her parents. She has learned for herself the grammatical rule that says ‘to form a past tense, add -
ed to the verb’, by hearing words like
rubbed, walked, and
cooked many times, and then applying the rule without consciously knowing what she is doing. She obviously knows what a verb is too, and you can be sure her parents have never mentioned the words
verb or past tense to her. What she has yet to learn is that a large number of verbs in English are irregular, and don’t form a past tense by adding -
ed, though she will have heard lots of them, including
drank, bent, drew, slept and so on.