This brief study is dedicated to the aspect of Lipps's scientific career which happened to be decisive for the first shaping of Husserl's phenomenology, and of the "phenomenological movement", in Munich and Gottingen. After a short survey of Lipps's biography and production, the author characterizes Lipps's original positions concerning general psychology and logics. A close examination of Lipps's letters to Husserl and Husserl's answers, as well as the new methodological approach developed by Lipps after 1902 allows to ascertain a simultaneous evolution of both thinkers : whereas Lipps comes closer to a phenomenalistic conception and practice of psychology, Husserl on his part tends to a more radical form of phenomenology, eidetical and antipsychologistic. This double shift is the context that helps enlightening the birth of the first generation of "phenomenologists".