Louis Agassiz sheds insight into Brazil's history: his travels took place in the 1860s, when the country was undergoing great change as an Empire and grappling with its this development.

The author offers accounts of a Brazil now lost to time; observations of the urban culture and life, and the natural habitat of the countryside and forests, offer immense insight into the era. Most of the text is written as a narrative diary, wherein Agassiz observes and describes traversing colonial-era Rio de Janeiro, the city of Manaus, the Amazon river, various villages, and the vast rainforests.

As a zoologist, Agassiz's interest in the wildlife present in Brazil form a recurring theme. However, the text is careful not to dwell on matters obscure or scientific; while the author at work, he also covers matters of culture and day-to-day life. Anecdotes include Brazil's Emperor Pedro II arranging room chairs that he sits equally with other attendees - reasoning that science does not distinguish people by position.