Chernaik gets the incredible essence of this: how he offloaded his difficult emotional world onto an imaginary band of alternative identities, partly for survival, to fight the philistine world on better terms. I wish she had dug a bit further into the way he translated them into music. Florestan’s characteristic gesture, for instance, is a surge: a crescendo with no corresponding diminuendo. (Schumann’s music is full of these instructions, all in a row; if you took them literally, you would end up playing louder and louder until you or the piano fell apart.) Eusebius’ gesture is the circle: a phrase that bends back on itself or oscillates around a mysterious center. The difference is not just contrast. Some of Schumann’s most compelling music holds these two forces in tension — centrifugal and centripetal, reaching and enfolding. He’s therefore able to tap into two veins of tenderness, one overtly adult-sensual, the second magically on both ends of the child-parent bond — young wonder plus aged reverie. In other words, the masks allow Schumann to capture love as a spectrum: He gets more of it than his fellow Romantics, even Chopin, with whom love can sometimes feel like a performance.

Chernaik, drawn to this supercharged story and the music, has backed up her affection with solid research. She describes the key family drama with relish: Robert’s initial infatuation with his piano teacher’s daughter Clara, the rage of the father once the romance is discovered, endless separation, legal wrangles and (at last) some reconciliation. (Once he is happily married, the real troubles begin: Schumann’s gifts waging war with the forces tearing him apart.) She narrates plainly, staying far from Schumann’s overeffusive style. It isn’t a gripping book for the person who already knows Schumann’s music and story, but it is perfect for the newcomer, a generous and tremendously useful resource.

Schumann’s elusive genius has allowed for a lot of naysayers. In a recent Wall Street Journal review of this same biography, the writer gives credit to Chernaik’s narrative work but can barely find time to praise Schumann’s music. He refers to Schumann’s spirit as “exhausting,” poking fun at his ardor: “Today’s reader might confront such a person and ask him to calm down.” He lists standard concert works but omits almost all the essential ones: the joyous, meltingly beautiful Piano Quartet; the Violin Sonata in A minor; and the surge of early piano pieces, including “Carnaval,” “Kreisleriana,” the “Fantasie” and — for many pianists the holiest of holies — the “Davidsbündlertänze,” a piece that rewards each listening more than the last.

Though I don’t understand them, Schumann doubters do have rational objections. Unabashed love and rational skepticism are natural companions, even symbiotic enemies. Schumann understood this as well as anyone. The final song of “Dichterliebe,” for instance, gives voice to the bitter, skeptical breakup phase of a relationship: “I’m done with it all.” The music is ironic, marching, strict, pitch perfect in its adopted pose of detachment. But after the singer goes silent, Schumann uses the pianist for an astounding catharsis. First, a hint of melody, syncopated against a hidden beat, ascending to some unknown goal. Then this melody gathers itself, trying to say something in the absence of words, reaching up once, twice, and a third time reaching the top of the arc of loss (while the singer remains mute, listening to his own sorrow). This phrase arrives without arriving, as life often does; when at last it recedes through various painful notes, you get something like comfort, but with all preceding heartbreak folded in. When you contemplate these great Schumann passages, humble, vulnerable and unflinching in the face of human emotions, it feels heartless to doubt.