Ferenczi's striving for mutuality, a call which Freud didn't take up, let him explore this concept with his analysands. He thus became the originator of mutual analysis, although with caveats, and of the concept of introjection, another important Ferenczian notion. The analyst's attitude of knowing the ‘objective’ and independent Truth is changing its orientation into that of a co-construction in the analytic work; here the analyst and the analysand build a third internal world, which they share and which remains their own. Clinical vignettes illustrate the implications of these views.