Eiseley writes in the tradition of the eighteenth century English natural-history essayists, such as Gilbert White and W. H. Hudson, and of the American nineteenth century personal essayists Ralph Waldo Emerson and Henry David Thoreau. In this tradition, the essayist records responses to nature while preserving the aesthetic sense, in contrast to the modern scientific essay, which is expected to avoid any suggestion of the writer’s voice. Eiseley combines the two traditions, though his essays draw more directly on science as a specialized body of knowledge than do earlier essays such as Thoreau’s. At times his literary voice conflicts with his scientific voice, and he expresses the tension between the two. Because he believes that science alone cannot make life bearable, he seeks to interweave science and poetic understanding.
Eiseley is aware of the natural-history essayist’s role in disseminating information. He notes the impetus given to evolutionary studies by the eighteenth century parson-naturalists who, though not scientific specialists in the modern sense, provided the broad, humanistic view of the world and of life that was necessary to develop evolutionary thinking rather than the narrow, scientific view of observation and classification. In an increasingly specialized world, where even specialists fail to communicate with one another, Eiseley views the popular essay as a means of communicating, not only specific scientific facts but also concepts that will make possible an interdisciplinary cultural awareness of science. As he interprets science, he points out to the intelligent general reader the dangers of institutionalized science: its single-minded pursuit of knowledge at the expense of the environment, its pursuit of space at the expense of other avenues of knowledge, its tendency to remain enclosed within its own specialties, and its encouragement of hero worship. From his position as a scientist, Eiseley is able to foster a thoughtful and critical perspective on the scientific establishment as well as on time and the creativity of evolution. Darwin, whom Eiseley studied in depth, was himself “a master artist and he entered sympathetically into life.” Such sympathetic participation in all of life is the concern of the literary naturalist, of the poet who embraces sympathy; it is the essence of Eiseley’s humanism.