In the present text, we explore the idea of dialogue at the heart and roots of the Leibnizian philosophy and present show its connection with the doctrine of the continuum. We shall argue that a dialogue, political, religious as well as doctrinal, constitutes the starting point of the Leibnizian conciliatory "humanist metaphysical" method of his demonstrationes catholicae. We shall see also that the idea of dialogue constitutes the metaphysical foundation as well as the practical goal of the most famous project by Leibniz, the caracteristica universalis, "Méthode de la Certitude et de l'Art d'Inventer pour finir les disputes, et pour faire en peu de temps des grands progrés". The connecting role of the dialogue within the Leibnizian thought is explained on three levels. First, on the level of metaphysics, we shall analyze from the metaphysical perspective the possibilities and limits of the dialogue in the horizon of human knowledge. Next, on the level of method, we shall discover the function of dialogue in the dynamics of the human invention. Finally, on the level of the drawing on Leibnizian writings, we shall document the virtus of the dialogue, as compared to the geometrical method.