As Husserl argues in the fifth Cartesian Meditation, the similarity of my Body (Leib) with the body (Körper) of another person is the founding moment of the experience of the other. This similarity is based on the previous objectivation of my Body. Husserl continuously worried to explicate this similarity-premise and by doing so, it appeared that this objectivation already presupposes intersubjectivity. By running into this problem, the Meditation actually fulfils its program by showing that the other is co-constitutive of the world and more precisely of my existence as a worldly human being. At the same time he developed an alternative approach by identifying the original experience of the other as an expressive unity (Ausdruckseinheit) as the condition of possibility of intersubjective experience. By drawing on the relevant Forschungsmanuskripte in the volumes on Intersubjectivity and on Ideas II, it appears that the Meditation offers a naturalistic theory of intersubjectivity that results from the introduction of the reduction to primordiality. When one takes into account Husserl's analysis of the experience of an expressive unity, that is a defining characteristic of the personalistic attitude, one can clarify the derivative nature of this naturalistic approach.