Ondine is less a species than an individual water sprite who, in many varied tellings, falls in love with a man at considerable risk to her immortality and/or his life. the subject of countless European folk tales and literary works such as Jean Giraudoux’s drama “Ondine,” performed by We Players at Sutro Heights last summer. Katharine Sherman’s “Ondine” for Cutting Ball, though no less densely poetic, is a very different type of drama — an extended tone poem on love, alchemy, breath, water and sleep deprivation. Luxuriantly staged by Rob Melrose, and performed with athletic grace and playfully sensual intensity by Jessica Waldman and Kenny Toll, it’s less a story than a reverie within the legend’s tragic climax, interrupted by flashbacks to moments in the romance up to this point — that gradually reveal its significance. The reason (remember the spoiler alert) is the curse she’s laid on him, that if he falls asleep he’ll stop breathing — not, as in many versions, because he’s been unfaithful to a woman but because he’s left her home alone too long in pursuit of his passion for alchemy. Knowing that adds considerably to the complex beauty of Sherman’s lyrical interplay of alchemical, emotional and culinary interactions with the rhythms of breath and the sea. Even the brightly staged visits of her sea-nymph sisters (Molly Benson, Marilet Martinez and Danielle O’Hare) begin to seem repetitive. [...] the danger of a theatrical reverie about fighting off sleep is that it may make you feel the same.