Writing a 15-page essay is difficult; writing a 15-page publishable paper is even more difficult. But writing a 15-page essay that is publishable and consistent in all its content is a masterpiece.
As difficult as to writing so many pages is to write a single paragraph that is structured in a readable, rational and valuable way. By readable I mean that is grammatically correct. By rational I mean that its sentences are all logical, valid and non-contradictory. By valuable I mean that achieves the goal of informing and adding value for the specific target of people for whom you are writing.
To learn how to do this and continue perfecting the “art” of writing I went through a course a year ago that used the book “The Art of Nonfiction Writing. A Guide for Writers and Readers” written by Ayn Rand as the main literature. The book is a magnificent tool that analysis different steps of the Writing Process by dealing it as an “ability to create quality nonfiction; a skill that can be learned like any other.”