Blackthorne reveals Europe and the Pope’s division of the world to Toranaga

Blackthorne reveals Europe and the Pope’s division of the world to Toranaga during an audience that begins as an inquiry into the foreign pilot’s background and becomes a confrontation with the reach of European power. Using a map drawn in sand, Blackthorne links the secret navigation manuals that brought him to Japan with Portuguese and Spanish trade routes, papal claims, and the possibility that Japan itself has been assigned to Portugal. The lesson gives Toranaga practical intelligence, but its most consequential revelation is political: distant religious and legal authorities have claimed a right to determine the fate of lands and peoples they have never governed.

The audience and the map

Toranaga asks Blackthorne to explain his family, country, queen, history, customs, ships, weapons, trade, wars, and navigation. The breadth of the request makes Blackthorne laugh: Toranaga wants nearly everything he knows. The questioning takes place in a guarded garden, where Browns keep their distance while ten Grays sit together watching the boy. The arrangement gives the exchange a political audience as well as a private instructional purpose.

When paper is not immediately available, Blackthorne kneels and draws in the sand, turning the rough map upside down so that his listeners can see it. He explains that the Earth is round but that a flat map represents its surface in stretched sections, and identifies Mercator’s method as a recent means of making such a map useful for navigation. He marks north, south, east, and west, locates Japan and his own country on opposite sides of the world, and distinguishes known coastlines from immense unexplored interiors. The map is not merely a picture of distant geography: it is a working instrument for explaining where ships can travel and who controls their passage.

Toranaga then asks him to trace the voyage to Japan. Blackthorne describes crossing the Strait of Magellan, waiting six months for favorable winds, and choosing that route because Portuguese forts and warships made the alternative passage around the Cape of Good Hope dangerous for his Dutch expedition. He says the Spanish use the strait to reach their Pacific American colonies and the Philippines, or cross the narrow isthmus of Panama to avoid a longer sea passage. The account challenges the assumption that Portuguese ships alone can arrive from the south and makes Blackthorne’s knowledge of the rival routes a strategic asset.

Rutters and the routes of power

The explanation depends on the value and limitations of the rutter, a pilot’s record of how to reach a destination and return. Such a manual could set down compass courses, soundings, water color and seabed, depths, currents, winds, seasonal storms, safe anchorages, places to careen and replenish a ship, reefs, shoals, tides, havens, and possible friends or enemies. Where charts were vague and longitude could not be fixed, this accumulated practical observation could make the difference between a navigable route and being lost out of sight of land.

Blackthorne says that Portugal and Spain guard the routes beyond European waters as national secrets, especially passages to the New World, through the Strait of Magellan, and around the Cape of Good Hope. He identifies the rutter he carried as a secret document copied from Portuguese materials by Pieter Suyderhof, a Dutchman who had served as private secretary to the Primate of Goa. In Blackthorne’s account, Suyderhof used access to documents held by a powerful church official who was also the Portuguese Viceroy, copied rutters describing routes and hazards from Goa through Macao to Japan, and later sold them to the Company of East India Merchants. Blackthorne’s own copy, lost with his ship’s papers, is therefore more than a personal possession: it contains information he says could be valuable to Toranaga.

He also describes Suyderhof as a Dutch spy who placed agents aboard Portuguese ships and argues that Portuguese India depends on Japan’s trade. Toranaga asks for a detailed paper map marking Portuguese bases and the number of ronin at each. The request turns geographical disclosure into intelligence gathering: ports, routes, garrisons, and commercial dependence can all be read as parts of the same contest for control of the sea. Blackthorne’s knowledge remains imperfect, however. A rutter can contain copying errors or deliberate falsehoods, and even a careful pilot cannot be certain of it until he has sailed the route himself.

The claim over Japan

The conversation becomes more dangerous when Toranaga asks why Blackthorne had been in the north. Blackthorne explains that his ship had searched for a northeast passage, then introduces a legal claim that sounds to Mariko like nonsense: Spain and Portugal had signed a treaty dividing the undiscovered world between them, and Japan lay within the Portuguese share. Toranaga responds with derision, comparing the claim to an imagined division of the heavens between himself and the Emperor of China. Blackthorne insists that the European division is not simply a boast by either king; he says it rests on documents granting Catholic rulers authority to claim non-Catholic lands discovered by their subjects and replace existing governments with Catholic rule.

To make the consequences concrete, Blackthorne traces the division through Brazil and the Spanish-held territories of the Americas. He describes conquest as a process in which military superiority, religious conversion, local rivalries, and exploitation reinforce one another. In his account, Portugal has become wealthy through Brazilian gold and silver, while Spain has accumulated wealth from Mexico and Peru after the destruction of Inca rule and the enslavement of many people. The lesson shifts from abstract boundary lines to the human and political consequences of European expansion.

Blackthorne attributes the authority behind these arrangements to the Pope. He recounts the line established by Pope Alexander VI in 1493, changes sanctioned by Pope Julius II and embodied in the Treaty of Tordesillas in 1494, and the later Treaty of Saragossa in 1529. On the sand, he draws a second line of longitude through the tip of southern Japan and says the agreement assigned Portugal exclusive rights to Japan and other parts of Asia. In his explanation, that exclusivity was justified as a means of spreading Catholicism but also enabled exploitation and intensified rivalry over the valuable trade with China.

Doubt, evidence, and consequence

The claim unsettles Mariko, who must translate it as Toranaga and the others wait. Toranaga suspects that Blackthorne may be trying to poison him against his enemies and demands the truth on Blackthorne’s life. Blackthorne responds with named dates, popes, treaties, and lines on the map, drawing on the historical and geographical knowledge taught to him by Alban Caradoc and on information he says he learned from Friar Domingo. The specificity makes his account testable in principle, but it does not make every part of it independently verified in the moment.

Mariko offers a qualification rather than a simple confirmation. She reasons that when the papal decisions were made, the countries concerned were Catholic, before the religious schism, and so the decisions would have been treated as binding within that Christian world. Even so, she recognizes the contradiction between Portugal’s claimed exclusivity and the continuing Spanish-Portuguese dispute over the wealth of Japan’s trade with China. Kiri judges that Blackthorne believes what he is saying, but asks how the claim, or any part of it, can be proved. The scene therefore leaves a gap between credibility and proof: the map and the treaties expose the scale of the threat as Blackthorne understands it, while his listeners still have to decide what can be trusted.

The exchange changes Toranaga’s questions from a general inquiry into a demand for usable intelligence. He wants a paper map, the Portuguese bases, and their manpower; Blackthorne has already said that many of the forts employ Japanese troops and that he knows their locations. The disclosure does not itself establish that Toranaga accepts every claim, but it gives him a new framework for interpreting the foreigners around Japan: trade, missionary activity, military posts, and navigation belong to a connected struggle over access and sovereignty.

The episode also gives Blackthorne’s earlier maritime experience immediate political force. His teacher’s lesson about the wealth promised to anyone who could solve the problem of longitude, the secrecy surrounding rutters, and the practical risk of sailing without reliable charts all converge in the map he draws for Toranaga. Later, when Rodrigues pilots Toranaga’s galley away from the coast and into open water, Blackthorne understands why that decision is risky and how a vessel’s course depends on wind, distance, and the pilot’s judgment. In the later pursuit by the Santa Theresa, he assesses the frigate’s need to tack against the galley’s freedom to maneuver. The audience’s account of European routes is thus not detached exposition: it establishes the navigational knowledge on which Blackthorne’s value, and the political possibilities of sea power, depend.