This paper considers the fundamental change introduced by Ferenczi in 1919 by proposing the use of countertransference as an instrument. Basically it reconsiders the concept of analytic neutrality; mastery of countertransference is reached through tolerating it, overcoming resistances against it, demanding a very intense involvement of the analyst, as opposed to the image of the surgeon or the mirror. The paper analyzes the implications of this position for psychoanalysis. It places these concepts in the scientific and personal context in which it was written, then follows the later developments of these ideas in Ferenczi's own work, as well as in that of some other authors, and comments on the effects of these ideas on the psychoanalytic movement. Finally it poses some questions regarding our present use of countertransference in clinical work, with two brief vignettes highlighting these points.