Sarah Manguso writes short, wildly ambitious memoirs. Her first, The Two Kinds of Decay, published in 2008, chronicles the rare and highly debilitating autoimmune condition that dominated the first half of her twenties. Her book is about the illness as much as it is about the way that we talk about illness — her particular condition is so uncommon it doesn’t even have a real name. The disease is known as chronic idiopathic demyelinating polyradiculoneuropathy, and Manguso’s recollections are an unsettling mix of the inconceivable and mundane. She writes of eating French fries in the hospital while having her plasma replaced through a central line in her chest, and noticing that the plasma in the waste bag appeared pale and cloudy, presumably from the lipids in the French fry grease. “After we figured that out, I ate French fries every time my plasma was replaced,” she writes. Later, she describes the intense gratitude felt toward the one nurse in the hospital who took care to wipe her ass completely, as she was too weak to do it herself. Though the book brims with dark humor, Manguso’s renderings of the helplessness of her condition are terrifying. “All autoimmune diseases invoke the metaphor of suicide,” she writes. “The body destroys itself from the inside.” Her second memoir takes suicide itself as subject: The Guardians (2012) is an elegy to her friend, Harris, who escaped from a psychiatric hospital and jumped in front of a train. In it, Manguso challenges societally acceptable processes of grief and contemplates the insufficiency of language in representing such suffering. Her books are fragmentary, ebbing in and out of time in a way that feels quite reminiscent of memory itself as she considers subjects that she acknowledges evade full understanding. Her earlier books include the story collection Hard to Admit and Harder to Escape (2007), and poetry collections Siste Viator (2006) and The Captain Lands in Paradise (2002). She is the recipient of the Academy of Arts and Letters’ Rome Prize and is a Guggenheim fellow. Ms. Manguso spoke with Erica Schwiegershausen via phone following her recent move to Los Angeles.