Nothing is more false than the image of Dante as an isolated genius standing out against his epoch. On the contrary he belongs to a very characteristic generation of italian intellectuals: laymen, often active in more than one domain, practicing abundantly poetic expression, engaged in political action, these scholar-citizens share equally a strong historical conscience. Their inventivity is manifested in philosophy, in medecine and in law, as well as in literary expression. Aside from these endogenous factors, a key to this phenomenon is linked to the active reception of the naturalistic knowledge elaborated in Paris, which is read in Italy outside of the control of theologians. The parallel journeys of a dozen uncommon personalities show the necessity of enlarging the habitual frames of medieval intellectual history.