We cannot tackle the concept of Federalism without also consider its antithesis, that is, Unitarianism and their mutual interaction in the development of Italian political thought from the end of the XVIII century. These two doctrines have been the gravitational poles around which Alberto Mario's political thought developed. The patriot of Lendinara in fact moved gradually from Mazzinian Unitarianism, in his acquaintances and in his youthful studies, to Cattaneo-style federalism; and only in the last years of his life he sought a summary, achievable also in practice, between these two conceptual systems.