Abraham (along with Mária Török) worked within the Freudian paradigm, but as fleshed out by the findings of Sándor Ferenczi; and indeed extended both—as with his concept of 'a parasitic inclusion', an extension of 'introjection, as defined by Ferenczi'. Together with Török 'he introduced several key concepts of contemporary psychoanalysis: the family secret, transmitted from one generation to the next (theory of the phantom), the impossibility of mourning following the emergence of shameful libidinal impulses in the bereaved before or after the death of someone (mourning disorder), secret identification with another (incorporation), the burial of an inadmissible experience (crypt)'.