Ammianus Marcellinus Res Gestae 27.4.14

[14] Now it is well known, as constant reports have spread abroad, that almost all the country folk who dwell in the high mountains throughout the lands just described surpass us in health and strength, and in the prerogative (so to speak) of prolonging life; and it is thought that this is due to abstinence from a conglomeration of diet and from hot baths, ¹ and a lasting freshness knits their bodies through cold sprinklings with dew; and they enjoy the sweetness of a purer air; further they are first of all to feel the rays of the sun, which are by their own nature life-giving, before they are infected with any stains from human affairs. After having thus given an account of these matters, let us return to our task.