The Calcolo geometrico (1888) seems to have been a turning point in the scientific career of Giuseppe Peano (1858?1932) because with this book he started publishing in logic. Looking for motivations of his early interests in the field one is naturally led to investigate the background of that book. Besides his previous work in mathematical analysis, methods and results of some Italian mathematicians and?above all?the spread of Grassmann's theories in Italy played a significant role: this point seems to have been (...) often underestimated by the historians of the subject. The connections between Calcolo geometrico and other related areas are also discussed. Peano's handwritten remarks and references taken from his own working copy of the Calcolo geometrico constitute the appendix of the paper. ?Simbolismo da alas ad mente de homo? (Peano 1913, 390). (shrink)