We must learn from the wiseness of words, but we must be able to distance ourselves from them. When studying Odyssey we note a first opposition between fictional islands, known only from sailors’ accounts, and real islands, inhabited or visited regularly. But the description of the former is as informative as the study of the latter. The epic in the western islands, all seemingly fictitious, has its own history indeed. It codifies and fixes in writing oral instructions intended for sailors and warriors of the protocolonial times (9th-7th century bc) and relative to navigation and to the singularities of peoples established in those other worlds. It thus gives a beginning of anthropology of the western world, such as Homer’s Greek contemporaries imagined it. The author gives a precise interpretation of extracts from Odyssey relative to navigation in the light of the several nautical expeditions he conducted in the Mediterranean with the assistance of specialists in ethnography, meteorology, history, linguistics, hellenism.