Some great composers were also great letter writers, producing correspondence that makes gratifying reading for everyone, not just musicologists. Yet in the book world today, where translations of letters can be anathema to publishers, dazzling epistolary artists like the Flemish composer Roland de Lassus (1532–1594) and the Frenchman Emmanuel Chabrier (1841–1894) remain untranslated into English. Fortunately, Mozart (1756–1791) does not labor under the same obscurity. Doubtless because of Mozart’s superstar status, his delightful missives have not been neglected in English translation, yet a lucid new translation by Stewart Spencer, “A Life in Letters: Wolfgang Amadeus Mozart” (Penguin Classics, 648 pages, $17) offers welcome original perspectives. Unlike previous rival selections, this new Penguin volume is not limited to letters by Mozart himself. The whole Mozart family gets into the act, and a zesty bunch they are.

As edited by the Mozart expert Cliff Eisen, the Penguin volume offers a counterpoint between the giddily joyous letters of young Wolfgang and the earnestly caring epistles of his father, Leopold. In letters to friends, Leopold reports on the progress of his 8-year-old son, already an acclaimed keyboard performer, whom he calls “Herr Wolfgangus” and “our heroic Wolfg.” Leopold explains how he has decided against allowing his son to be vaccinated for smallpox, and is duly anguished some months later when the little boy does indeed fall ill with the disease. Leopold’s doting admiration develops into hysterical protectiveness, especially when Wolfgang starts touring with his mother, sister, or by himself, leaving his father at home in Salzburg.

Meanwhile, Mozart exults in his own facility for producing music “like sows pissing” as he states in a letter from 1770, although he repeatedly complains that his fingers hurt “from writing so many recitatives.” Family toilet jokes are expressed with earthy gusto, as when Mozart’s elder sister, Nannerl, adds a postscript to a 1777 letter to their father: “Keep well till we’re back, stick your tongue up your crack. And then s— in your bed.” Such fecal advice alternates with violent criticism of the inhabitants of Salzburg and Paris, and accounts of dimwitted music students and envious professional rivals.

When Mozart’s mother dies in 1778 while he is traveling with her, the composer expresses himself to family and friends in conventional terms: “God has called her to Him … her life snuffed out like a candle.” This is in distinct contrast to the uncanny originality of Mozart’s musical meditations on death, like the “Requiem” in D minor, K 626, or “Mass” in C Minor, K.427. Yet there is a musical aspect to Mozart’s belatedly announcing the fatal news to his father in order to prepare him for the shock. Doing so, Mozart creatively transposes and manipulates time in his letters, much as he does in his music. And his prose and compositions share quicksilver mood changes. The same letter in which Wolfgang first informed his father of his mother’s death continues with the comment: “I couldn’t help laughing at your account of [a rival composer’s] drunkenness.”

Today’s reader, aware that Mozart’s life will be short and full of professional strife, may find some observations all too poignant, as when he states from Paris in 1778: “I see here a crowd of miserable bunglers, all of whom are able to get on, so why shouldn’t someone as talented as I am be able to do so?” Mozart died — probably from rheumatic inflammatory fever, according to Mr. Eisen — at age 35, mouthing the sound of the tympani from his “Requiem” in D minor. Our solace is to experience the music itself in fresh new performances by youthful voices like the French soprano Véronique Gens and British tenor John Mark Ainsley in Mozart’s early opera “La Finta Giardiniera” on DVD from Deutsche Grammophon, or from Decca DVD, an eloquent new performance by the refined Mexican tenor Ramón Vargas in the title role of Mozart’s 1781 opera “Idomeneo.”

In terms of unappreciated talent, it is worth noting that the Penguin Classics series tends to be taken for granted, and rarely granted review space in the press, yet it often contains material newly available in English of undisputed worth, like Richard Sieburth’s translation of prose by the French writer Gérard de Nerval; the poetry of Pierre de Ronsard translated by Malcolm Quainton and Elizabeth Vinestock; and Eduard Mörike’s poetry and prose, rendered by David Luke. All of these superlative translations — like the stellar work by Stewart Spencer for this precious new volume of Mozart’s letters — deserve every English-language reader’s thanks.

Mr. Ivry last wrote for these pages on the critic Norman Lebrecht.