‹‹‹ Vitr. 1.4.6 | Table of Contents | Vitr. 1.4.8 ›››
7If any one doubt this, let him study the different natures of birds, fishes, and animals of the land, and he will easily perceive the truth of these principles, from the variety existing among them. For there is one flesh of birds, another of fishes, and another, very different, of land animals. Birds have a small proportion of earth and water in their nature, a moderate quantity of heat, and a considerable portion of air; whence, being light by nature, from their component elements, they more easily raise themselves in the air. Fishes, by nature adapted to the watery element, are compounded of but a moderate degree of heat, a considerable proportion of air and earth, and a very small portion of water, the element in which they live; and hence, easier exist in it. Wherefore, when removed from it, they soon die. Terrestrial animals, being constituted with much air, heat, and water, and but little earth, cannot live in the water, on account of the quantity of that element naturally preponderating in their composition.
7If one wishes a more accurate understanding of all this, he need only consider and observe the natures of birds, fishes, and land animals, and he will thus come to reflect upon distinctions of temperament. One form of mixture is proper to birds, another to fishes, and a far different form to land animals. Winged creatures have less of the earthy, less moisture, heat in moderation, air in large amount. Being made up, therefore, of the lighter elements, they can more readily soar away into the air. Fish, with their aquatic nature, being moderately supplied with heat and made up in great part of air and the earthy, with as little of moisture as possible, can more easily exist in moisture for the very reason that they have less of it than of the other elements in their bodies; and so, when they are drawn to land, they leave life and water at the same moment. Similarly, the land animals, being moderately supplied with the elements of air and heat, and having less of the earthy and a great deal of moisture, cannot long continue alive in the water, because their portion of moisture is already abundant.