"Portuguese Letters" is a classic literary masterpiece, which was published in 1669 and to this day remains a hallmark of French prose of the 17th century. The authors of these letters are considered to be the French writers Gabriel Joseph de Lavergne and Viscount Guillaume de Guierrag – the pseudonym of Gabriel Joseph. In their "Letters of the Portuguese", the authors tell the love story of the Portuguese nun Mariana and the French waitress. This book has inspired many generations to be creative and express themselves through letters that reflect the deepest feelings and emotions. The publication of the book with an introductory essay by Alexander Piedaniel makes it even more accessible to the modern reader, because it helps to better understand the context and meaning of this literary work. "Portuguese letters" remain relevant in any era, revealing to the reader the depth of feelings and sensations that are eternal and unchanging in the world of love.