The author's main purpose in this book is to teach precision in writing; and of good writing (which, essentially, is clear thinking made visible) precision is the point of capital concern. It is attained by choice of the word that accurately and adequately expresses what the writer has in mind, and by exclusion of that which either denotes or connotes something else. As Quintilian puts it, the writer should so write that his reader not only may, but must, understand.
For me Ambrose Bierce was always a mixed bag. Still is. While there is much to commend the opinion above, by its strictures much of what we call literature from the Ancient Greeks to the present day would not exist. The writer writes to be understood, but also to mean beyond the page--one cannot circumscribe the connotations of ever word, and thus there are times when one cannot obey these dictates in their strictest form.