Finally we get down to brass tacks. We already pointed out that you, the person preparing the manuscript, must to play the role of typist and editor. As editor you have the job of telling the printer how large to make chapter titles, what typeface to use for chapter titles, how much space to skip above and below a chapter title, etc. Having to give this set of instructions every time you want to type a chapter title can get to be a pain in the neck. Not only that, but imagine the problem of remembering exactly what format you want for chapter titles, section titles, subsection titles, etc., if – as is the case with PHYZZX – you use a different format for each one. Clearly, if one had to type all of this each time and keep all this information in one's head one would probably choose not to use TEX at all.
This discussion raises another point, namely that if one did not have a predefined set of macros to tell TEX what to do at a certain point then you would have one more job dumped upon your shoulders. In addition to being typist and editor you would have to be a book designer. That means that you would have to make all of the esthetic decisions about the most attractive print to use for a given paper, the spacing to use between lines, the best way to number equations and the rest of that crap. This can be an onerous task which the average user doesn't want to have to deal with. Moreover, everybody has his own esthetic criteria (even though some people have more taste than others), so without a macropackage, to set the formats into predefined molds, there would be little or no uniformity in the layout of papers coming out of SLAC. While this would be no great tragedy, it could get confusing.
Okay, so PHYZZX is a macropackage which provides a dictionary of editor's commands which allow one to easily format a document for the printer. It makes a set of esthetic choices for how these documents should look and, in the interests of simplicity, doesn't make it trivial for the casual user to mess around with these choices. (Actually, this is not really true since there are many ways in which PHYZZX can be tailored to your personal preferences, but we will discuss that as we go along.) The obvious question which comes up at this point is Who made all of these esthetic decisions?. In the interests of preserving the lives of the parties involved, anonymity must be preserved. Rest assured, however, it was a consultative process and many people had an input into the final result. Despite the fact that PHYZZX is an animal put together by a committee, we think it does its job fairly well.