In Spinoza there is no such a thing as a proper analysis of ‘madness’: the lexicon that belongs to its semantic area does not play a particularly relevant role in his writings. In the Ethics, the presence of the term delirium especially in books III and IV reveals madness' explicit link to passions and highlight their pathological side (see for instance the definitions of pride, avarice, ambition, etc.), whilst the frequent usage of it alongside somnium and insania in the Preface to the Theologico-Political Treatise polemically exposes the phantasmagorical side of imagination and the strong impact of superstition on collective imagination. However, in chapter XVI of the Tractatus, where Spinoza expounds the main traits of the universal natural law, he uncompromisingly declares that there is no difference between men and the other individuals in Nature, neither between those endowed with reason and those without, nor – as a consequence – between ‘idiot’ (fatui) and ‘mad’ (delirantes) people and those of ‘sound mind’ (sani). These statements shed a light on the extreme modernity of Spinoza's reading of ‘madness’ and psychic disorders (and of imagination: not only vitium, but also potentia), and show that he paves the way to some important themes of 19th century antipsychiatry. This testifies, once again, the great fecundity of his thought in the theoretical context of other cultural systems, also in our age (etnopsychiatry, psychoanalysis, social sciences).
