Alpheus Sherwin Cody (November 30, 1868 - April 4, 1959) was an American writer and entrepreneur who developed a long-running home-study course in speaking and writing and a signature series of advertisements asking Do You Make These Mistakes in English? A critic of traditional English education, Cody advocated colloquial style and grammar. His course, presented in a patented workbook format which he described as self-correcting, was purchased by over 150,000 students from its inception in 1918. He published essays, books and articles virtually nonstop from 1893 through 1950. In a book published in 1895, he gave the advice, Write what you know-so go out and know something.