Epidaurus in 293, by which time she may have been admitted (which was not the case before) into the Epidaurian family of the god. Her proper name as a Romanized Greek importation was Valetudo, but she was gradually identified with Salus, an older genuine Italian divinity, to whom a temple had already been erected in 302. While in classical times Asclepius and Hygieia are simply the god and goddess of health, in the declining years of paganism they are protecting divinities generally, who preserve mankind not only from sickness but from all dangers on land and sea. In works of art Hygieia is represented, together with Asclepius, as a maiden of benevolent appearance, wearing the chiton and giving food or drink to a serpent out of a dish. See the article by H. Lechat in Daremberg and Saglio's _Dictionnaire des antiquités_, with full references to authorities; and E. Thrämer in Roscher's _Lexikon der Mythologie_, with a special section on the modern theories of Hygieia. HYGIENE (Fr. _hygiène_, from Gr. [Greek: hygiainein], to be healthy), the science of preserving health, its practical aim being to render "growth more perfect, decay less rapid, life more vigorous, death more remote." The subject is thus a very wide one, embracing all the agencies which affect the physical and mental well-being of man, and it requires acquaintance with such diverse sciences as physics, chemistry, geology, engineering, architecture, meteorology, epidemiology, bacteriology and statistics. On the personal or individual side it involves consideration of the character and quality of food and of water and other beverages; of clothing; of work, exercise and sleep; of personal cleanliness, of special habits, such as the use of tobacco, narcotics, &c.; and of control of sexual and other passions. In its more general and public aspects it must take cognizance of meteorological conditions, roughly included under the term climate; of the site or soil on which dwellings are placed; of the character, materials and arrangement of dwellings, whether regarded individually or in relation to other houses among which they stand; of their heating and ventilation; of the removal of excreta and other effete matters; of medical knowledge relating to the incidence and prevention of disease; and of the disposal of the dead. These topics will be found treated in such articles as DIETETICS, FOOD, FOOD-PRESERVATION, ADULTERATION, WATER, HEATING, VENTILATION, SEWERAGE, BACTERIOLOGY, HOUSING, CREMATION, &c. For legal enactments which concern the sanitary well-being of the community, see PUBLIC HEALTH. HYGINUS, eighth pope. It was during his pontificate (c. 137-140) that the gnostic heresies began to manifest themselves at Rome.