However, Sérgio, who was neither a geographer nor a historian but rather a stimulator of minds, knew how to complement his text with purpose-drawn diagrams that illustrated his points (it should be noted that Sérgio had naval training, and he did not refer to these sketches as maps). In his geographical introduction, he declared that he did not believe that “the geo-physical characteristics of our land explain the existence of the political entity known as Portugal.” He argued that in “all of medieval Europe, the new states that emerged seemed to be the result of the will of leaders and their accompanying warrior class, without any racial, national, or tribal basis” (Sérgio, História, p. 43). This allowed him to propose his theory, namely that the key factor was the territory’s position within the Peninsula, especially the “ports for European maritime-commercial activities and the value of the coastline and climate for exploiting marine resources (fishing, salt)”. "The northern peoples needed salt and were not in a position to obtain it from the sea; the climate of the Portuguese, unlike theirs, was ideal for salt production: therefore..." (Sérgio, História, p. 42). This was the main thesis Sérgio sought to defend, which provoked the anger of his political opponents, who were attached to an agrarian monarchy with integralist overtones. Sérgio argued that Portugal “was only of primary importance as a supplier of products derived from maritime exploitation: fish and salt.” He continued, “The northern peoples needed salt and were not in a position to obtain it from the sea; the climate of the Portuguese, unlike theirs, was ideal for salt production: therefore…” (Sérgio, Emtôrno, pp. 43 e 51). To some extent, his main argument, aligned with Silva Telles, his co-author of the Guia de Portugal [Guide to Portugal] i n 1923-1924). For Sérgio, who was neither a geographer nor historian, it was necessary to use “geographical-historical notions that help us understand certain aspects of history where the land and humankind appear united as correlating factors of social evolution” (Sérgio, História, p. 51). Thus, Orlando Ribeiro would state that the “relationship between history and geography is correctly positioned—provided the author follows through with the programme he has outlined .” (Ribeiro, Introduções, p. 147).