«Why create a work when it is so beautiful to just dream about it?». Pasolini's Decameron ends with this question; and 'dream' is the keyword that summarizes the meaning of the artistic-cultural operation carried out by the first act of the Trilogy of Life. Among the ancient Italian phrases recorded in Francesco Serdonati's paremiographic collection we find «A dream: A vain thing. Somnium». In Pasolini's Decameron the dream is an expression of the poetics of the unfinished, in some respects connectable to the history - sometimes very ancient - of the idiomatic components of current (and recurring) language: fragments of an interminable «force of the Past» of which the poetdirector felt part and expression. Starting from the screenplay, I intend to propose a summary of Decameron's sentences, accompanied by reflections on their typology and reuse techniques, always keeping in mind the comparison, on the one hand, with Boccaccio's model and, on the other, with Serdonati's collection. What emerges leads to new considerations on Pasolini's style, on his relationship with literary models, as well as with erudite paremiography, with the history of the Italian language, with popular tradition and with dialects. There will be no shortage of comparisons with the transcription of the film's speech. [ABSTRACT FROM AUTHOR]