A writer, contrary to the popular opinion, does not write books.
A writer writes texts.
The fact, that a text is contained in a book, comes only from the dimensions of such a text; or, in the case of a series of short texts (poems, for instance), from their number.
A literary (prose) text contained in a book ignores the fact that the book is an autonomous space-time sequence. A series of more or less short texts (poems or other) distributed through a book following any particular ordering reveals the sequential nature of the book. It reveals it, perhaps uses it; but it does not incorporate it or assimilate it.
Written language is a sequence of signs expanding within the space; the reading of which occurs in the time.
A book is a space-time sequence.
Books existed originally as containers of (literary) texts.
But books, seen as autonomous realities, can contain any (written) language, not only literary language, or even any other system of signs.
Among languages, literary language (prose and poetry) is not the best fitted to the nature of books.
A book may be the accidental container of a text, the structure of which is irrelevant to the book: these are the books of bookshops and libraries.
A book can also exist as an autonomous and self-sufficient form, including perhaps a text that emphasizes that form, a text that is an organic part of that form: here begins the new art of making books.
In the old art the writer judges himself as being not responsible for the real book. He writes the text. The rest is done by the servants, the artisans, the workers, the others.
In the new art writing a text is only the first link in the chain going from the writer to the reader. In the new art the writer assumes the responsibility for the whole process.
In the old art the writer writes texts.
In the new art the writer makes books.
To make a book is to actualize its ideal space-time sequence by means of the creation of a parallel sequence of signs, be it linguistic or other.