The "Historia Naturalis" of Pliny includes a description of the heavens and the earth; the position and course of the celestial bodies, the meteoric phenomena of the atmosphere, the form of the earth's surface, and everything relating to its productions, from the plants and the mollusca of the ocean up to the human race. According to Humboldt, all these subjects were treated of and applied, in the most varied way, and brought forth the noblest fruit of descriptive genius. The elements of general knowledge were copiously employed in this great work, but without strict order in the arrangement. "The road over which I am about to travel," says Pliny, with a noble pride, "has been hitherto untrodden; no one of our nation, or of the Greeks, has alone undertaken to treat of the entire subject, namely Nature. If my enterprise does not succeed, it is, nevertheless, a fine and grand thing to have attempted it." The intelligent author attempted an immense picture, and did not entirely succeed; but the want of success depended principally upon a want of capacity to make the description of nature subordinate to scientific generalizations, and in view of the comprehensive laws of creation. Eratosthenes and Strabo had referred, not only to a description of mountains, but to an account of the entire earth; of their investigations, however, Pliny made but very little use. Not more did he profit by Aristotle's work on the anatomical history of animals. As overseer of the fleet in lower Italy, and as governor of Spain, he had but little time for extended research in natural science, and was often compelled to commit the execution of large portions of his designs to inferior hands.