The growing interest among music theorists in the historical theory of form from the Classical period has significantly changed the way we listen to and understand many canonical works. In Mozart’s time, the structure of a composition was based on clearly articulated nodal points, determined by a series of cadences and related to the appropriate disposition of thematic elements and the overall tonal plan. These cadences were differentiated and hierarchised through reference to linguistic metaphors: different cadences corresponded to different punctuation marks, with different degrees of ‘closure’. Such an approach can also be applied to Witold Lutosławski, whose music draws on Classical models, transforming them to a great extent. The peculiarity of Lutosławski’s syntactic structures lies in his use of several unsynchronised syntactic layers (as can be seen above all in the contrasting melodic and accompaniment layers). However, these different syntactic sequences are interdependent and generate mutual adjustment processes, resulting in a form that is both strictly composed (with the use of mathematical procedures regulating the development of each of the layers and their mutual interactions) and ambiguous in perception (a particularly strong effect of such ambiguity is the blurring of the point of reprise). Comparison of the Bucolics and Postlude No. 1 reveals the ongoing development of polysyntactic techniques during the critical period of transition from the neoclassical to the ‘avant-garde’ phase in Lutosławski’s œuvre.