The question of arbitrary or motivated nature of the linguistic sign is back now thanks to the contribution of neuroscientists (Ramachandran, Rizzolatti). We aim to combine the phonosemantic approach they propose with the principle of arbitrariness defended by most linguists (Hurford, Auroux). Alterative Italian suffixes are difficult to reduce to our method, because they form an open set of lexemes with very irregular features. However, it is possible to describe a diagrammatic relationship between their phonological and semantic systems. In particular, the semantic opposition between {dimensional} and {axiological / affective} values corresponds to a phonological opposition between [simple] and [complex] consonants (-ino, -one, -etto vs -accio, -uzzo, -astro). The semantic opposition between {small} and {big} values tends to correspond to a phonological opposition between [front acute] and [back grave] vowels (-ino vs -one, -etto vs -otto). Finally, the semantic opposition between {axiological pejorative} and {diminutive affective} corresponds to a phonological opposition between [open] and [closed] vowels (-accio, -azzo, -astro vs -uccio, -uzzo, -iccio). All these relationships can be described as figurative diagrams, interpreting articulatory gestures as physiological metaphors of semantic values.