Vigorous writing is concise. A sentence should contain no unnecessary words, a paragraph no unnecessary sentences, for the same reason that a drawing should have no unnecessary lines and a machine no unnecessary parts. This requires not that the writer make all his sentences short, or that he avoid all detail and treat his subject only in outline, but that every word tell.
This quote from William Strunk was noted by E. B. White in the 1959 introduction to his revised edition of Strunk’s Elements of Style, which had first been published by Strunk in 1918 and used as a textbook in his classes at Cornell (one of which White attended in 1919). By 1959, it already had become a classic on how to write; it remains one today.