Celce-Murcia Article

The Marianne Celce-Murcia article "Language Teaching Approaches" discussed the various methods of TESOL learning throughout history.  I thought it was interesting how very little work had been done prior to the 20th century and how much work has been done during the 20th century based on the amount of information and research done in the field.  I thought that her perspective that there have been so many changes in recent decades has been because teachers were not aware of the other methods.  I have to wonder what language learning teachers must have thought with all of this change, and what teachers in the pre-20th century must have felt about the way they taught?  It is an interesting concept to think of because the little amount of study that seemed to have taken place in the area of TESOL.