This article takes as its starting point the various versions ( and ) of Beyond the Pleasure Principle. In these versions, different and sometimes contradictory biological theories and principles play a crucial role in the argumentation. In the first version of the text, the references to Lamarck and Haeckel in particular are meant to support a metapsychological reflection starting from the clinical problem of traumatic neurosis. In the second version of the text, and with the introduction of a new drive theory, the focus shifts to an endogenous productive principle (the life drives). This shift implies a clear nuance and perhaps even undermining of the biological principles on which Freud oriented himself in the first version, and the significance of trauma and repetition. In the two versions of the text, Freud positions himself in different ways in the debates of his time in biology and the philosophy of the life sciences – between mechanistic and vitalistic approaches.