In the image Christopher Columbus is discovering America in 1492. The discover of America was a monumental point i history as it opened infinite possibilities for many countries and revolutionize the asset of power and history itself. For many historics, the discovery of America is to be considering the begin of the modern world.
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The meaning of the image could be multiple. First of all it shows an important historical event, and that is the first meaning. Then, there is the meeting of new cultures. Maybe even a foreshadowing of the massacre of some years later of the native cultures. Moreover, a representation of history and its diversified layers.
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As for the oggettive part, the notes is enough evidence. Then, there is the fact that one part of the people are dressed and the other one is naked, which is a known simbol in most western cultures to indicate native or "primitive population". The three boats is another sign that the paiting is associete with the figure of Christopher Columbus.