From Clear and Simple as the Truth: Writing Classic Prose, by Francis-Noël Thomas and Mark Turner (Princeton University Press, 1994):
“[W]riting is an intellectual activity, not a bundle of skills. Writing proceeds from thinking. To achieve good prose styles, writers must work through intellectual issues, not merely acquire mechanical techniques.”
I think this is correct—even though it’d be a heckuva lot easier if writing were nothing more than “a bundle of skills.” But, for me anyway, the thinking part of the equation is arguably more important than the actual writing—even though it’s the first to get tossed overboard when deadlines loom.