The paper redefines the analytical view of the Mozartian piano concerto KV 467 in a theoretical framework where the starting point is allegory, together with the formal structure. This level of values consists of metaphors, and figurative expressions. Morality as exo-signs is transformed into endo-signs and gain a central position in performance. Formal properties do not hold a primary ontological position in a musical work. Due to Hume's moral sentimentalism values are based on sentiments and feelings not rationality. Beliefs arise based on sentiments that cause virtues and vices to arise. Thus, one gets from sentiments to the higher level of values from where allegory can be reached. This enlargement of the explanatory framework increases the factual nature of the allegorical input, while it at the same time questions the validity of the fact-value distinction. First ritornello in concerto KV 467 launches the modality “May” without specifying what the possible states of affairs will be. During research inference proceeds from ought to is. Processes of becoming normative and finding the general principle through reflective equilibrium are simultaneous. Then the model can convey knowledge about alternatives for theory of virtues based either on religious doctrine or on 18th century empiricist philosophy. What were formerly moral exo-signs in the work's formal structure have through existential semiotics now become endogenized and turned into endo-signs. To support the analysis of individual identity of concerto KV 467 as an Enlightenment allegory both sonata form and ritornello principle will contribute to the formation of this equilibrium.