The most glamorous philosopher of the Italian Renaissance, and in many respects the most contemporary, died in the autumn of 1494. He was just thirty-one. Giovanni Pico della Mirandola came from aristocratic stock: the Pico dynasty ruled Mirandola, a tiny northern Italian principality, from a fortified castle that still bears the family name. At the time of his death, Count Giovanni Pico had mastered a Babel of ancient languages, nettled the Pope, done jail time in France, developed an unhealthy fixation with the Dominican friar and religious fundamentalist Girolamo Savonarola, dabbled in magic, and written a sunny treatise, “Oration On the Dignity of Man,” which became the anthem of the Renaissance.

The tragedy of Pico’s death, as well as the memory of his brief, incandescent life, has been revived in recent years. In 2007, his remains, together with those of the man who may have been his lover, the scholar-poet Angelo Poliziano, were disinterred from the Dominican Convent of San Marco, in Florence. Both contained toxic levels of arsenic. The results confirmed the suspicions of the doctors who examined the bodies in 1494 (poison was the murder weapon of choice, the digestible bullet, in Renaissance Florence) and brought Pico’s name back into circulation. His death has become the subject of a Florentine murder mystery: a five-hundred-and-twenty-year-old cold case. Who killed Pico della Mirandola? And why?

In December, 2013, Italy’s self-styled leading art detective, Silvano Vinceti, called a press conference in Florence with what he claimed were new findings. Vinceti was the head of the committee that had exhumed the bodies, six years earlier. At the press conference, Vinceti proposed a solution to the mystery, set in a political shadow world at the intersection of Medici power, papal authority, and fundamentalist religious hysteria. Pico, in Vinceti’s view, was assassinated on the orders of Piero de Medici, the son of Lorenzo the Magnificent.

Even without the whodunit speculation, the bare facts of Pico’s death are harrowing. He took almost two weeks to die. The king of France, Charles VIII, who was marching from Pisa to Florence at the time (he would take the city on the day of Pico’s death) dispatched his own physicians to tend to the great mind of the age. They arrived too late. Pico fell into a kind of accepting swoon, calm and tranquil. “He asked also all his servants' forgiveness, if he had ever before that day offended any of them,” Thomas More wrote in 1504, in his brief life of the young Count.

Pico’s prodigious powers of recollection are legendary. “Do you think that I have the same memory as Pico della Mirandola's?” the former Italian President Giorgio Napolitano huffed in exasperation in a Palermo appeals court late last year, when he was being grilled over events from two decades before. Even by the lofty standards of the Renaissance, Pico was a freak. He could recite Dante’s Divine Comedy backward, starting with the last line of Paradiso. By the time he was twenty, he had studied at the universities of Bologna and Ferrara and learned Latin (the language in which he wrote and thought), Greek, Hebrew, Arabic, Aramaic, and Chaldean. He was the first Christian philosopher to tackle the mysteries of the Kabbalah. Throw in his aristocratic background, his height and heft—he was solidly built and six feet tall—along with his green eyes and a shoulder-length mane of wavy chestnut hair, and you have an appealing package.

But more important than his presentation was the animating ambition of his work, which is startlingly relevant today. It was as much theological as philosophical. For young Pico, there were no walls separating the sages of Christianity, Judaism, Islam, and pagan antiquity; they existed side by side. The director of Milan’s Pinacoteca Ambrosiana, Don Alberto Rocca, cuts to the essence of Pico’s jarring, challenging contemporaneity. “He was attempting to bring the world’s religions together,” he says. “But I fear now they have broken apart.” If Pico’s ideal of a rapprochement between religions, and between religion and philosophy, is relevant to our agonies, it is apposite in a negative way: it invokes an opportunity lost, or at least disappearing from view.

Last year, the scholars Giulio Busi and Raphael Ebgi poured more oil on the coals of the Pico controversy in a new book, “Giovanni Pico della Mirandola: Mito, Magia, Qabbalah” (“Giovanni Pico della Mirandola: Myth, Magic, Kabbalah”). The work concentrates on Pico’s intellectual and moral range—his challenge to the Church, his relationship with Savonarola, his interest in Platonism and Kabalistic theories, his philosophical interest in beauty—and on his search for esoteric meanings hidden beneath the surface of Old Testament narratives. He spent his days and nights truffling through texts for symbols, much like a semiotician. “Pico is contradictory and must be accepted as a cultural agitator,” Giulio Busi, the director of the Institute of Jewish Studies at the Free University of Berlin, says. “He was much more transgressive than we are usually willing to admit.”

In 2007, Pico’s remains, together with those of the man who may have been his lover, the scholar-poet Angelo Poliziano, were disinterred from the Dominican Convent of San Marco, in Florence. Both contained toxic levels of arsenic.

The surviving work that best captures the breadth of Pico’s learning and the largeness of his spirit is his “Oration.” (The title is something of an upsell; the speech was never delivered.) It begins with a statement of intent: “Most venerable fathers, I have read in the records of the Arabians that Abdul the Saracen, on being asked what thing on, so to speak, the world’s stage he viewed as most worthy of wonder, answered that he viewed nothing more wonderful than man.” The “Oration” was written in 1486. Just more than thirty years earlier, Constantinople had fallen to the Ottoman army of Mehmet II. What had been, for a thousand years, a Greek-speaking Christian empire—no less than the continuation of Rome—was now a Muslim caliphate. It was not exactly a prudent time to proclaim the wisdom of Islam. But that was Pico.

In the very next sentence, he reels in a mysterious author from late antiquity named Hermes Trismegistus, who was highly esteemed by both Christian and Muslim thinkers (though scholars today doubt his very existence). He goes on to cite a piece of ancient Persian wisdom and to buttress it with a fragment of Psalm 8. There is a set piece on “those things that I have dug up from the ancient mysteries of the Hebrews,” a celebration of certain memorable Arab writers, and a discourse on the splendors of the Greeks.

The approach is a little more than bits-and-pieces eclecticism. The technical term is syncretistic: a harmonizing or synthesis. Pico’s boast—“that I may base myself on all teachers of philosophy, examine all writings, recognize every school”—could so easily have resulted in an unappealing Esperanto spirituality. But that’s not what he has in mind. Every school has “something notable that it does not have in common with the others.”

The lines that seem to declare a break with the old world and a desire for the new one come in an imagined address to Adam by his maker: “Neither heavenly nor earthly, neither mortal nor immortal have we made thee. Thou … art the molder and maker of thyself; thou mayest sculpt thyself into whatever shape though dost prefer.” In time, this imperative—at once protean, libertarian, and egoistic—would gird the edifice of Western individualism.