Federalism is mainly understood to be an organizational principle in which the individual members (member states) have a limited independence and statehood, but are united to a sovereign overarching federal state.
A federal state consists of sub-states that exercise certain (limited) competences under constitutional law that are not derived from the federal government as a whole. In addition to the state as a whole, the member states of a federal state therefore have their own, original autonomy over the population in their territory in terms of constitutional law.
He’s trying to say that it would be almost impossible to continue their journey without having an important part of his mind outwards and shared with the world
