The birth of scientific psychology was proclaimed at the turn of the 19th and 20th centuries, a time characterized by an "embarrassment of riches" (Bühler). The present series aims to make accessible this wealth - a wealth often overlooked by the exclusively epistemological debates around psychologism or by the dominance of naturalistic currents little interested in their own precursors. Specific attention will be paid to texts which contain conceptual and empirical approaches particularly likely to be reexploited in current debates around the nature and laws of the mind. Indeed, two ways of thinking about psychology developed in the past - one inspired by phenomenology, the other by biology - are clearly on the rise today. A real exchange between past and present will thus be played out by the reissuing here of historical texts.