Two or Three Tasks, Not One
There are three distinct tasks in writing a book: composition, document structuring and page layout. The first two are closely related, though maybe not in the way we usually think. The third is independent of the process of composition.
Page layout is essentially typesetting - putting the words and spaces down on a page for readability, and having regard to document structure. Structuring a document is deciding and informing the system, during composition mostly, which bits of content are, for instance, margin notes, footnotes, titles, section headings. Composition is the process during which one writes bits of a document, moves sections around, inserts graphics, does search and replace - and in general, gets thought onto paper, though not necessarily in final form at a first draft.
It is almost impossible to write a document of any length without doing Structuring as a part of Composition. You and the application you are using both have to know what bit of a document you are writing. However, it is perfectly possible, and desirable, to compose, including the necessary structuring, without doing any page layout at all as you do it.
Lets try to make this clearer, because it is probably an unfamiliar concept.
You can see the confusion between tasks that most packages lend themselves to if you look at heading styles. When you pick 'heading 1' in a Word Processor, you simultaneously pick some print style elements, like Helvetica 16, bold, inset 5 spaces. This is Layout. At the same time, you are telling the system that this is a top level section heading. This is Structuring. It is logically possible to do one without the other. It is quite possible to tell the system this is a top level section heading, and have it display in Times 12 red, but have it make an independent later decision to print in Helvetica 16 black. You also often decide, in making a given element a section heading, that what follows will be a moveable chunk. You will mostly be able to drag this chunk around. But this too should be independent of font, indentation and so on.
You can also see the confusion if you look at pagination and word count and section numbering. Normally a WP program will tell you which page you are on, and you may well use that as a guide to where you are in the document. But which page you are on is a page layout/print function. The number of words is the document authoring function. The position in the logical structure of chapters and sections is a document authoring function. The position in the content is what matters for composition, not the position in the spaces that determine page layout. In Lyx, which totally separates layout and composition, you have no way of knowing pages until you go to PDF view or DVI view. But you always can tell how many words you have written, and where you are in the logical structure.
In fact, in Lyx, you use a carriage return to tell the system that it has just ended a paragraph. In the display this puts in a line feed, so you the author can see your para has ended. However, this may result in a much larger or smaller space in the printed output, depending on what class you are using, and multiple returns will not put in any more space. The system already heard you!.
The effect is, that you never have to think about spacing when writing a document in Lyx. But on the other hand, you do always have to tell the system what parts of your document it is dealing with - chapters, headings, sections, footnotes, bibliographies.
There are, then, two kinds of tasks in what we usually think of as laying out the document. Task one is to tell the system how to classify a given chunk of your document as being of a certain kind. This task is inseparable from Composition, and we've been calling it 'Structuring'. You will usually write a document and think about content in logical parts. That is, you will do Composition and Structuring at the same time. Structuring will be part of the Composition process. Task two, layout proper, is to determine a typesetting implementation to display these parts appropriately on a printed page. This is something which we need not and should not do while composing.
