During the interwar period in German-speaking countries music theory was profoundly influenced by the vitalistic and energetic philosophies which emerged in reaction to positivism. Several authors similarly reacted against the 19th-century ‘Formenlehre’ tradition, refusing the typological approach to syntax and form still predominant in the teaching of composition, which they considered merely superficial. A true and more complete understanding of form could be achieved only by looking beyond the surface of the notated score in order to identify deep structures or latent forces intended as metaphysical foundations of the musical phenomena. Relying on partly common philosophical premises, Ernst Kurth and Heinrich Schenker were among the few theoreticians who went as far as to propose completely new concepts of form, trying to sketch a new ‘Formenlehre’. Their radical diversity notwithstanding, their theoretical and analytical approaches share the problem of the relationship between deep and surface musical processes, which this paper will directly deal with. In the first section I will draw on Kurth’s explicit definition of form as a tension between a metaphysical force and its coercion in outlines (i.e. the score) in order to explain some philosophical aspects of Schenker’s theory of form that remain implicit and can be only deduced by some of his apparent digressions. In the second section I will investigate from a meta-theoretical perspective the relationship between structure and form in Schenker’s Der freie Satz in order to clearly distinguish the realization of the structure in terms of its diminution (vertical axis) from its truly formal realization in terms of its progression through time (horizontal axis).