In discussing "The Firmament of Time", Professor of Zoology Leslie Dunn wrote, "How can man of 1960, burdened with the knowledge of the world external to him, and with the consciousness that scientific knowledge is attained through continually interfering with nature, 'bear his part' and gain the hope and confidence to live in the new world to which natural science has given birth? ... The answer comes in the eloquent, moving central essay of his new book." "The New Yorker" wrote, "Dr. Eiseley describes with zest and admiration the giant steps that have led man, in a scant three hundred years, to grasp the nature of his extraordinary past and to substitute a natural world for a world of divine creation and intervention ... An irresistible inducement to partake of the almost forgotten excitements of reflection." A review in "The Chicago Tribune" added, "book has a warm feeling for all natural phenomena; it has a rapport with man and his world and his problems; ... it has hope and belief. And it has the beauty of prose that characterizes Eiseley's philosophical moods."