Serpentum et Draconum Historiae

Behold, the serpent grows young again, its cast-off skins removed,
And it refreshes its weary limbs from their heavy state.

Tibullus, indeed, contemplating this property of serpents, lamented the human condition in this manner:

Cruel gods! The serpent sheds its old age,
But the fates have granted no such respite to human form.
Old age is shed by snakes with a thin skin,
Why are we trapped in such a narrow condition?

Book 16.

Using this property of serpents as an argument, Joannes Spondanus, in his commentaries on Homer’s Odyssey, attempts to confirm the Paracelsian doctrine of the philosopher's stone.
Book 1. de temp. c. 5.

This reasoning, however, could never appeal to us. Galen, too, led by this serpentine property, demonstrated that serpents cannot grow hair; because these animals, hiding in a subterranean cave during the winter, acquire dry skin in the manner of testaceous animals; therefore, hair cannot emerge from it, and for this reason they shed it in the spring. Although there have been many of the opinion that white snakes cast off their old age at the rising of the Dog Star, we judge this to be far from the truth; for this is not observed in Italy, nor can we be brought to believe that even in hotter regions of the world, snakes leave their skins behind so late. As for the cause, however, because of which serpents lose their old skins every year, authors differ among themselves in their opinions. The poets, who are always stirring up fables, assign the cause of this to Jupiter, who once, for sacrifices, granted youth to men who had deserved well of him, sending it by a pack-ass; but the beast sold such a treasure to the snakes for a simple drink of water. Georgius Sabinus explains this myth in most elegant verses in this manner:

Why serpents shed their skins.

Book 4, Elegy 3.

At the time when Jupiter assumed the empire of Olympus,
And, having driven out his father, gave laws to the gods,
The common people performed sacrifices to the Thunderer
With the blood of bulls; a festive day was held throughout the world.
Jupiter, moved by these rites, swore by his scepters
That whatever they asked would be granted.
The crowds of men gathered, and all begged for a youth
That no old age could ever harm.
The Almighty assented, and called the slow ass
On which the aged foster-son of Bacchus was wont to ride.
"Take these," he said, "and bring these gifts to the pious mortals."
The ass fulfilled the mandate commissioned by Jove.
What have you to do with such a gift, most wretched of beasts?
A heavy burden of logs would be more suitable for you.
Behold, as the weary creature collects his thirst while traveling,
He turns his path toward the streams of an irrigated spring.
The snake, guardian of the liquid pool, saw the quadruped
Carrying such gifts, and said:
"You shall have no share of drinking from this stream
Unless you give to me the gifts you carry on your back."
Alas, cowardly beast! The ass sells a gift
Nobler than heavenly nectar for base water.
Old age is shed by snakes with a changed skin,
But sad fates await us as old age presses upon us.
And let him beware of entrusting anything to crude asses
Who wishes for his affairs to be well managed.

Book 1. Phar. cap. 23.

But omitting the trifles of the poets and approaching serious matters, we assert that one must read the very learned Quercetanus on this subject, who attributes it to a certain balsam which is contained in the bosom of the earth as in its proper place, matrix, and seed-bed; and therefore, so that serpents may cast off their old skin and don a new one, they suck this balsam from the entrails of the earth, and especially while they lie hidden without food during the coldest months. For they are necessarily nourished at that time by this precious balsam of nature, by which all things are animated and vegetate; by the aid of which, thereafter, in the springtime, all things revive and become flourishing. And
Opinion of Quercetanus.