First published in 1916, MOUNTAIN INTERVAL is Robert Frost’s third collection of poetry, following A BOY'S WILL (1913) and NORTH OF BOSTON (1914). His Contemporaries on the Poetry of Robert Frost:He not only sees things but sees things in their relations; and he knows that not only is everything related to every other thing, but that all things are related to the eternal mystery, their source and their goal. This is why the yellow primrose is so infinitely more than a yellow primrose. This also explains why the poems of Mr. Frost, after stirring us to glad recognition of their fidelity, leave us in a revery. — William Lyon Phelps in THE ADVANCE OF ENGLISH POETRY IN THE TWENTIETH CENTURY Mr. Frost writes down exactly what he sees. But, being a true poet, he sees it vividly and with a charm which translates itself into a beautiful simplicity of expression. He is an eminently sympathetic poet. He wins first by his gentle understanding, and his strong and unsentimental power of emotion; later, we are conquered by his force, and moved to admiration by his almost unapproachable technique. — Amy Lowell in TENDENCIES IN MODERN AMERICAN POETRY