Camões chief source for the details of Vasco da Gama's voyage was a diary kept by one of his crew members. The diary is anonymous, but is attributed to either Álvaro Velho or, according to recent scholarship, João de Sá. The record of the voyage is nearly complete, as it covers the entire outward journey and the return as far back as Guinea (the current country of Guinea-Bissau). The work survives in a single 16th C. manuscript, which is now in the Biblioteca Publica or Public Library in Porto. The diary was published in 1838 from this manuscript:
To the best of my knowledge, as of this date, three English translations are available. In alphabetical order from most recent to oldest, these are:
- Ames, Glenn J. En nome de Deus: The Journal of the First Voyage of Vasco da Gama to India, 1497–1499. Leiden: Brill, 2009.
- Axelson, Eric, trans. Vasco da Gama: The Diary of his Travels through African Waters 1497–1499. Somerset West: Stephen Phillips, 1998.
- Ravenstein, E. G., trans. A Journal of the First Voyage of Vasco da Gama, 1497–1499. London: Hakluyt Society, 1898. Archive.org. Accessed 28 March 2021.
While the work was not printed until the 19th century, it must have begun circulating in manuscript soon after da Gama's return. Camões certainly had access to it, as many of the details in Os Lusíadas precisely parallel those in the diary. For example, the diary says that when the ships stopped at St Helena Bay, da Gama's crew captured one of the native inhabitants:
He was going about gathering honey in the heath, for the bees of that land place it at the foot of the scrub.
Camões writes that the captured man had been:
making his sweet harvest
Of honey from the wild bees in the forest.
This and other parallels are noted by Nicholas Meihuisen (p. 25), who describes the changes Camões makes to his source:
Putting the source and Camões side by side, one becomes aware of variances in attitude that might be ascribed, for instance, to the differing aims of the two writers in terms of both ends and means. One is a diarist, recording events in a factual, non-dramatic way. The other is an artist, adapting events in as dramatic a way as possible. The differences between the two works, though, also highlight ... blind arrogance in Camões. (p. 24)
There are several possibilities to account for Camões' access to this diary:
- He took a copy with him when he left Portugal for the East in 1553
- Manuscripts of the diary circulated among the Portuguese in Goa and/or Macau, and he encountered one there
- He revised his epic to make it parallel the diary after he returned to Lisbon in 1570 while preparing it for publication in 1572.
The third seems the least likely, as the parallels are sustained enough to suggest the poem must have been composed with the diary at hand.
Such parallels are of course to the specifics of da Gama's voyage. But much of Os Lusíadas comprises narrations of earlier Portuguese history; fabulous incidents, such as the Isle of Love episode in the last two cantos; or parallels drawn between the events being described and various mythological stories. For these, Camões drew upon his knowledge of history, his own imagination, and his study of classical literature, particularly Virgil and Ovid.