Duarte Pacheco Pereira probably made several voyages to west Africa before accompanying Afonso de Albuquerque to the East in 1503. There he was involved in the defence of the factory of Cochin and in the first serious fighting between the Portuguese and the Indians of Calicut. He returned to Portugal in 1505 and appears to have busied himself with the manuscript of his book, mysteriously entitled Esmeraldo de Situ Orbis. This work provides the first comprehensive account of Portuguese explorations and activities in western Africa. It is largely a compendium of geographical information, but the author incorporates much historical detail and gives his reflections on the peoples of the region and their relations with the Portuguese. He abandoned the manuscript unfinished around 1506, although he himself lived until 1533. It was first published in 1892.

This extract shows how the reputation of Henry ‘the Navigator’ had developed in the forty years since his death. Duarte Pacheco does not share either the doubts expressed by many modern historians concerning Henry's role in the peopling of the islands and the discovery of the upper Guinea coast or twenty-first century reservations about the slave trade. It was the wealth brought to Portugal by these discoveries, including the trade in 3,500 slaves a year, which for him was the principal reason why Portugal should honour the prince and pray for his soul.