This inept chalk drawing of a woman may have been the work of Michelangelo ’s young friend and admirer Tommaso de’ Cavalieri. COURTESY MUSEUM OF FINE ARTS, BOSTON/CASA BUONARROTI, FLORENCE, INV. 2F/ORGANIZED BY MUSARELLE MUSEUM OF ART AT THE COLLEGE OF WILLIAM AND MARY, WILLIAMSBURG, VIRGINIA.

This is a truly hideous drawing. Fat lips, a gaping mouth, buckteeth. Look at those eyes: the tentatively indicated right pupil is misplaced, and the left is an android-like bore-hole. This cannot possibly be a drawing by Michelangelo. Why has the Museum of Fine Arts, Boston, elected to include it in an exhibition of masterworks?

The reason becomes clear on the opposite side of the sheet. There we find the justifiably famous idealized head of a woman, traditionally identified as Cleopatra because of the snake encircling her breast and fastening its venomous bite on the left nipple.

Michelangelo presented the beautifully finished drawing of Cleopatra to his new friend and admirer, the Roman nobleman Tommaso de’ Cavalieri, in 1532. It is now one of the highlights of the Casa Buonarroti, the house museum bequeathed by Michelangelo’s heirs to the city of Florence in the mid-19th century, and is included in the exhibition “Michelangelo: Sacred and Profane, Master Drawings from the Casa Buonarroti” (April 21–June 30). Given the exceptional beauty of the drawing, one wonders how and why a weak and unappealing scrawl came to defile it? How do we explain the discrepancy in quality between the two sides of this sheet?

Despite the beauty of the Cleopatra, many earlier critics—including such distinguished connoisseurs as Bernard Berenson, Luitpold Dussler, and Frederick Hartt—rejected its attribution to Michelangelo. Berenson, for example, was put off by the degree of finish, writing that “the highly elaborated, smoothly finished design is likely to be either a failure or an absurdity.” Even when scholars accepted the sheet as autograph, they often found fault, especially with the peculiarly bulbous breast and the flat delineation of the masticating snake.

But the sheet has an impeccable and unbroken provenance, which is extremely unusual for a drawing. Now visitors to the Boston exhibition have a rare opportunity to judge it in person.

Michelangelo wielded the broad edge of his black chalk to exploit the natural texture, or “tooth,” of the paper, thereby creating the silken sheen and swarthy complexion appropriate to the queen of ancient Egypt. Precise contours describe the head and elegantly long neck, the soft sensuous lips, the saddened distant eyes, and an extravagant headpiece from which escape fluttering tendrils and a long tight braid. Cleopatra exudes an air of dreamy serenity: wistful, longing, silent, despite the slight parting of tremulous lips.

This masterpiece of the draftsman’s art is a finely finished miniature painting, much admired by Michelangelo’s biographer, Giorgio Vasari, who considered the Cleopatra a stupendous drawing (“una carta stupendissima”). No wonder that Michelangelo’s contemporaries praised such finely finished drawings as “perfectly painted” (“perfettamente dipinta”). The praise, however, makes it even more difficult to explain the grotesque, gorgon-like figure on the verso.

This figure was revealed when a thick backing sheet was removed in 1988. Scholars had long been aware of the presence of a drawing on the verso, but it was extremely difficult to discern, even when the Cleopatra was held up to the light. The revelation of a “new” work by Michelangelo was greeted with fanfare, but its inferior quality proved difficult to explain. Describing the drawing as a more “tormented” Cleopatra does little to justify its unsightly character and inarticulate draftsmanship.

Substandard sketches are present on the reverse sides of Michelangelo drawings on a number of similar sheets. These drawings are a byproduct of the artist’s patient if desultory pedagogical efforts. Occasionally Michelangelo used the same sheet on which a pupil had been practicing in order to demonstrate good drawing or “buon disegno.” Thus the sequence of creation was just the opposite of what is implied by our arbitrary designations of “recto” (front) and “verso” (reverse). In these pedagogical drawings, the so-called verso was drawn first, followed by the finished drawing on the opposite side, now called the recto merely because it is the finest drawing on a sheet.

So who is the inept draftsman of the Cleopatra verso, the first drawing on this otherwise magnificent sheet? I would suggest Tommaso de’ Cavalieri, the young man to whom Michelangelo offered drawing lessons and who was the first owner of the Cleopatra.

Michelangelo met Cavalieri in Rome toward the end of 1532. By all accounts, Cavalieri was extremely handsome, endowed with exquisite manners, physical grace, and a sensitive personality. Despite the difference in age and in social standing (Cavalieri was from a noble Roman family), the two experienced an instant mutual attraction and enjoyed a close friendship that lasted more than 30 years. And how did an old man (Michelangelo was considered old at 57) express his feelings for the admiring youth? With long, gushing letters, poetry, days spent looking at art together, and an offer to teach the young man drawing.

Cavalieri tried his hand by drawing the figure on the verso. Not yet a Cleopatra, the head may have been inspired by an antique sculpture that the two friends inspected together, such as the famous Sleeping Ariadne in the Belvedere Court of the Vatican. Or it may have been inspired by Giovanni Boccaccio’s Famous Women: is this Agrippina, the grieving wife of Germanicus, or the Carthaginian Queen Sofonisba just after draining the fateful cup of poison? However, Cavalieri’s halting effort fell short of its classical inspiration (the display of teeth had especially negative connotations). To demonstrate “buon disegno,” Michelangelo reversed the sheet and performed a miracle of artistic alchemy: ugliness became beauty, harrowing but unbecoming emotion became serene resignation, an indecorous head was transformed into a doomed Cleopatra. We are privileged witnesses of Michelangelo turning base matter into gold.

Cavalieri kept the Cleopatra for 30 years before he was constrained to donate it to Duke Cosimo de’ Medici in 1562. In the accompanying letter, Cavalieri lamented that giving up his treasured possession was no less painful than losing a child.

William E. Wallace is Barbara Murphy Bryant Distinguished Professor of Art History at Washington University in Saint Louis. His most recent book is Michelangelo: The Artist, the Man, and His Times (Cambridge University Press, 2011).