In his book on education written in 1912, Thorndike contrasts personal teaching with teaching via a textbook, and concludes thus:
If, by a miracle of mechanical ingenuity, a book could be so arranged that only to him who had done what was directed on page one would page two become visible, and so on, much that now requires personal instruction could be managed by print.
(Thorndike, 1923)
Today, almost 100 years on, can you think of examples of such 'miracles of mechanical ingenuity?'
Read more: University of Houston College of Education production on the History of Instructional Design