"As with her poetry, Glück's prose is fine and pared but visionary; her intelligence is precise and earnest. . . . Here and elsewhere Glück's brevity, clarity, and resolute independence are impressive." – Publishers Weekly
"With this book, [Glück] becomes the patron saint of poets and writers, having fallen and crawled and scared herself to a position from which she reticently gives advice." – Los Angeles Times Book Review
"This first collection of [Glück's] essays is written in a different medium [than her poetry], but it contains the same dark precision, the same spare fates and paradoxes. . . Proofs and Theories. . . is certainly a provocative book. . . it is the prickly poetic testament and memoir of one of America's finest poets." – Poetry Flash