(translated from Catalan)

“On the Day of the Book, your husband dedicates
you the life of Pau Casals.
Your admired and loved musician with your love each day.
Your husband
April 23rd”

Found by Xavier Caballé in Barcelona (Catalonia, Spain) who says:

“I bought this book in Sant Antoni (Barcelona), where every Sunday there are a lot of
used and old book street stores. The book was published in 1962 and it’s a biography
of Pau Casals, a virtuoso Catalan cello player.”

From Wikipedia

“El dia del llibre (The Day of the Book) is a Catalan holiday celebrated on April 23 similar
to Valentine’s Day with some unique twists that show the ancient practice of this day.
The main event is the exchange of gifts between sweethearts, loved ones and respected
ones. Historically, men gave their girlfriends and wives roses and women gave their
boyfriends and husbands a book to celebrate the occasion. In modern times, the mutual
exchange of books is customary. Roses have been associated with this day since medieval
times, but the giving of books is a more recent tradition. In 1923, a bookseller started to
promote the holiday as a way to honour the nearly simultaneous deaths of Miguel Cervantes
and William Shakespeare on April 23, 1616. Barcelona is the publishing capital in both
Catalan and Spanish and this heady one-two punch of love and literacy was quickly adopted.”