“Lerner [is] among the most promising young poets now writing.”—_Publishers Weekly_ “Sharp, ambitious, and impressive.” —_Boston Review_ National Book Award finalist Ben Lerner turns to science once again for his guiding metaphor. “Mean free path” is the average distance a particle travels before colliding with another particle. The poems in Lerner’s third collection are full of layered collisions—repetitions, fragmentations, stutters, re-combinations—that track how language threatens to break up or change course under the emotional pressures of the utterance. And then there’s the larger collision of love, and while Lerner questions whether love poems are even possible, he composes a gorgeous, symphonic, and complicated one. _You startled me. I thought you were sleeping In the traditional sense. I like looking At anything under glass, especially Glass. _You_ called _me_. Like overheard Dreams. I’m writing this one as a woman Comfortable with failure. I promise I will never But the predicate withered. If you are Uncomfortable seeing this as portraiture Close your eyes. No, _you_ startled_ BEN LERNER is the author of three books of poetry and was named a finalist for the National Book Award for his second book, _Angle of Yaw_. He holds degrees from Brown University, co-founded _No: a journal of the arts_, and teaches at the University of Pittsburgh.