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Finding Hidden Treasures: The Carvalho Monteiro Collection (part 1)

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When libraries incorporate other libraries, they acquire the physical books, but the purchase very often brings a whole number of stories behind each one of the items and the original collector. This blog will take on the journey of a very special and intriguing acquisition of a collection that transcends continents.

It is actually a quest. An “Indiana-Jones” kind of quest to find and bring to light a collection acquired by the Library of Congress almost a century ago containing highly significant and unique treasures spanning from the 16th through the 19th centuries and catalogued without provenance.

This quest takes us back to the year 1929, when the Library of Congress completed the purchase of a private library of approximately 30,000 items, considered the largest acquisition of that year: the Carvalho Monteiro Collection. This acquisition constituted the backbone for the creation of a new Division and reading room – the Hispanic Division (today Latin American, Caribbean and European Division), thanks to donated funds from Archer Huntington, a philanthropist and scholar, primarily known for his contributions to the field of Hispanic Studies.

But, who was Carvalho Monteiro and why was his library relevant?

Portrait of Carvalho Monteiro. Open access image from

Born in Brazil, but mainly educated in Portugal, Antonio Augusto de Carvalho Monteiro (1848-1920) was a lawyer, businessman, philanthropist, freemason, and entomologist, among other things. He discovered a significant number of plants and insects, especially butterflies, in Brazil and Portugal. He possessed an impressive natural history collection and traveled through Europe to contact experts. He liked to design his own catching equipment and even invented a umbrella with a modified articulated handle to collect butterflies. Because of his fortune, he was frequently referred to as Monteiro dos milhões (or Monteiro, the Millionaire). Known for his charity and generosity, he was one of the most influential figures of the late 19th century in Europe.

In addition, Carvalho Monteiro was an avid bibliophile and gathered a large private library of over 30,000 volumes, focusing on Portuguese culture and history and the flora and fauna of Brazil. He was also the greatest collector of works by and about Luís Vaz de Camões (1524/25-1580), considered to be one of the greatest Portuguese writers in history. Carvalho Monteiro’s library became an important source material on art, architecture, music, religion, history and decorative arts in a variety of languages including Portuguese, French, German, Spanish, Italian, Russian and Latin in the 19th century.

A renaissance man, no doubt!

The library was originally housed at his estate Quinta da Regaleira, a UNESCO World Heritage site, located in Sintra, Portugal. This magnificent property shows Carvalho Monteiro’s passions and beliefs in each component of the architecture and gardens featuring Pagan and Christian iconographies, a chapel, and an initiation well symbolizing the journey of man to enlightenment.

Looking down the Initiation well at Quinta da Regaleira (left). The Palace (right). Monogram Carvalho Monteiro (up right). Photograph by Beatriz Haspo, 2017.


Fountain (left). Chapel and detail on the ceiling inside (on the right). Photograph by Beatriz Haspo, 2017.

Following his death, his books and his other collections of coins, butterflies, and musical instruments were sold by his heirs and dispersed in Europe and South America. The Library of Congress purchased the Carvalho Monteiro’s library of 30,000 volumes, known as “the Portuguese Collection”,  from Maggs Bros. Booksellers between 1927 and 1929, with three acquisition numbers. Yet, despite this impressive purchase at that time, no acquisition list was made. This means that these acquisition numbers, which were either stamped or written on the verso of the title page of each volume, represent the unique and only identifier that the items belonged to the Carvalho Monteiro library.

Like some of the other private collections of books purchased by the Library in that time period, the books were cataloged without provenance or attribution to the collector and dispersed through the Library’s collections, according to media, including maps, music, manuscripts, and prints with the vast majority (around 23,000 items) going to the General Collections.

Acquisition numbers: 366768 ’27; 366768 ’28; 387270 ’29. Photograph Beatriz Haspo, 2022.

Fast forwarding to 2011, scholars from CulturSintra Foundation, which manages the Quinta da Regaleira, visited the Library of Congress hoping to see the Carvalho Monteiro library and obtain a list of contents. I was invited to attend their presentation and heard about this hidden library for the very first time. I was very intrigued by it and offered to try to locate some of the books. Easier said than done, as I realized later.

Just to put things into perspective, at that time, the General Collection consisted of almost 20 million books, pamphlets and bound periodicals. And I had to offer to find many thousands of items without a list. Where to begin?

Well, after learning about his passion for Camões, I did a general subject search in our bibliographic database right after the lecture and brought about 300 items to my office. I opened each volume looking for the acquisition dates. To my surprise, 95% of them had the stamp on the verso of the title page confirming they were part of the Carvalho Monteiro library.

So, I proposed a special project to search and identify all 30,000 volumes from the Carvalho Monteiro library and to virtually reunite them by adding the provenance to each record. I started coordinating this effort in 2012, focusing first on the 23,000 items dispersed in the General Collections, involving interns and volunteers from the United States and abroad and Library of Congress staff.

Since the only identifier was the stamp on the verso of the title page, we needed actually to find the physical book in the stacks to start the process. But, how do you search for 23,000 among millions? One cannot just go to the stacks and start opening every book, right?

Therefore, we started with clues from various sources, including topics, such as Portuguese, Camões, butterflies, botanic and combined with more elaborate searches based on the history and methods of cataloguing as well as space management practices under my responsibility. The clues generated targeted search lists, which we then took to the stacks to verify the actual books.

What an amazing feeling it is, every time when we open the book, flip the title page, and there is the stamp.

Stamp (in red) on the verso of the title page. Photograph by Beatriz Haspo, 2022

Each item found provided more clues for the next search, increasing the finding probability.

This is just the beginning of this treasure hunt. Stay tuned for the continuation on my next blog, when I will describe what happens after we find the volumes and how anyone can access the books found now.

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Comments (4)

  1. What an exciting treasure hunt and incredible long-term project!

  2. Great blog!

  3. How many have been found thus far?

    • Hi Mike, around 9,000 have been found so far.

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