It’s a fascinating book about a fascinating life. Lorenzo Da Ponte is known to us as the librettist of three Mozart operas: “The Marriage of Figaro,” “Don Giovanni,” and “Così fan tutte.” Together they are known as “the Da Ponte operas.” That’s immortality. When you’vehitched your wagon to Mozart, you’ve really hitched your wagon to a star.

The author of “The Librettist of Venice” (Bloomsbury, 448 pages, $29.95), Rodney Bolt, was born in South Africa and educated at Cambridge. He spent the 1980s as a writer and director in the London theater. And he now lives in Amsterdam. Mr. Bolt published his first book only two years ago: That was “History Play,” a “speculative biography” of Marlowe. Mr. Bolt may be a fairly rookie author, but he’s on a roll.

Three years ago, Richard Brookhiser was looking for a quick way to identify his latest biographical subject, Gouverneur Morris. He came up with a good one: “the peg-legged rake who wrote the Constitution.” Mr. Bolt (or his publisher) has come up with a good one for Lorenzo Da Ponte. The subtitle of this book — actually, one of two — is “Mozart’s Poet, Casanova’s Friend, and Italian Opera’s Impresario in America.” And there’s more, believe it or not.

Da Ponte lived in four different places — Venice, Vienna, London, and New York — at key times in their histories. Mr. Bolt’s book is therefore not only a biography, but a cultural study, or quartet of studies, treating the second half of the 18th century and the first quarter or so of the 19th.

This “librettist of Venice” was born in 1749 — in the ghetto. Oh, no, Lorenzo Da Ponte was nothing like his original name. That was Emanuele Conegliano. He had that name until he was 13, when his father had the entire family converted. The bishop performing the ceremony was Lorenzo Da Ponte — hence the adoption of that name by the eldest son of the Conegliano family.

Incidentally, in his memoirs — written at an advanced age — Da Ponte does not mention his Jewish background.

The boy’s schooling was fitful, and until he was 10 he could not really read and write. But eventually he found tutors and books, and he was enthralled with Pietro Metastasio, the poet of “opera seria.” (He was later to know him, as he knew just about everyone.) Metastasio is somewhat mocked today — as airy and formulaic — but he was a genuine talent, and he was a champion of the Italian language, which needed it.

Through twists and turns, Lorenzo became a priest. But he was not what you might call a model priest. He was a rake, and like many of them, he had loads of charm. People adored him, especially women, though maybe not their husbands. He was at the level of his friend Casanova. Da Ponte was always in trouble with the law, and in trouble with individuals. He impregnated many women, whose babies were sent to orphanages.

Mr. Bolt is pretty blithe about all this, rooting for our hero against stodgy foes who would hamper him.

In time, Da Ponte — having gone a few steps too far — was banished from Venice. He made his way up to Austria, which Mr. Bolt describes as “Maria Theresa’s severe and conservative land.” Uh-oh. But Maria Theresa obligingly kicks off, leaving the empire in the hands of her son, Joseph II. This man showed extreme kindness to Lorenzo, appointing him official theater poet. In the Vienna chapter of his life, he tangled with Salieri, among others, and had his fateful encounter with Mozart.

Why did Da Ponte quit Vienna, center of the universe? The reasons are several, but, in short, he ran out of luck. And Mr. Bolt points out that the general tide was turning. He writes, typically, that “an era of erotic flamboyance gave way to more prudish times.”

Shortly after Lorenzo departed from Vienna, something interesting occurred: He got married, did the Abbé Da Ponte. To an Englishwoman of the Anglican Church. In a synagogue. The bride was Nancy Grahl, whose mother was French and whose father was a German-Jewish convert. Thus did a ghetto-born Roman Catholic priest wind up marrying an Anglican in a synagogue. Only in America.

But, no, the couple wasn’t in America yet. They were married in Trieste, actually. They made a go of it in London — an exciting place in and around 1800 — before sailing to the New World. America was perfect for Lorenzo: a land of self-reinvention for an inveterate self reinventor. The Da Pontes lived in New York, but the poet could not find much literary work there — here, I should say. Italian was not a prized foreign language.So he made money in other ways — running a grocery, for example.

And, almost surreally, Lorenzo and Nancy moved for a spell to Sunbury, Pa. Imagine this extravagantly worldly figure, an adornment to imperial courts — Mozart’s librettist — in an early-American backwoods hamlet. And he enjoyed it, partly.

Back in New York, Da Ponte became a bookseller, and he did what he could to promote, or introduce, Italian opera. He also managed to get himself appointed professor of Italian at Columbia — the first such professor in the university’s history. He died in 1838, almost 90. The poet was buried in the Catholic cemetery on 11th Street. Later, that cemetery was dug up, and its contents were moved to Queens. No one can say which remains are Lorenzo’s.

I have said that Mr. Bolt has written a fascinating book, and it is also a dazzling book. A dazzling subject deserves a comparable chronicle. But, as he dazzles, Mr. Bolt takes some liberties, and if this is not quite a “speculative biography”— as that Marlowe book is labeled — it includes a fair amount of speculation. Also psychoanalytic indulgence.

Moreover, Mr. Bolt perhaps protests too much for Lorenzo. In his preface, he contends that Da Ponte has been slighted by history, as Mozart has grabbed the glory. But the sorry truth is, few of us would know Lorenzo’s name, if not for the undying greatness of that composer. We certainly wouldn’t know him for his librettos to operas by Vicente Martín y Soler. The poet himself seems to have come to a wise estimation of his place. As Mr. Bolt quotes,

To that immortal genius [Mozart] I gladly yield all the glory which is due to him for writing such miraculous works; for myself, may I hope that some small ray of this glory may fall on me, for having provided the vehicle for these everlasting treasures, through my fortunate poetry.