Complete Works, Vol. V

...and it is a sign of this that the stone which is called coral a marine stony growth is without a doubt generated from woods and plants. For sometimes in our time, in the Danish sea near the city of Lübeck, a large branch of a tree was found in which there was a bird's nest, and the magpies were in the nest, and they had been turned into stones, and they were small in the nest, leaning slightly toward a reddish color. This could not have been otherwise than because the tree was uprooted by storms or waves at the time when the nest was in it, and the birds fell into the water, and afterward, through the virtue of the place in which they were lying, everything was converted into stone.

Note on the generation of coral.

Note on the fountain in Gothia.

There is, moreover, a fountain in Gothia, of which it is most truly handed down that it converts everything immersed in it into stone; to such an extent that the Emperor Frederick sent a sealed glove to it to test the truth. When half of the leather and half of the seal had been immersed in the fountain for several days, the half of the leather and the half of the seal were converted into stone, while the other half of the leather remained as it was. It is also truthfully reported by trustworthy people that the drops which are scattered upon the bank of the fountain from the force of its falling are converted into stones, having the size of the drops; yet the water that flows in this way is not converted into stone, but flows continuously. We also see with our eyes crystals generated in the highest mountains, which are of perennial snows; this again cannot be, except through the virtue of the minerals that is in those places. From all of these facts, it seems that nothing certain can be handed down regarding the place of the generation of stones, since it does not occur in only one element, but in several, nor in only one climate, but in all.

Why stones are generated in the clouds

And what seems more wonderful than these things, they are generated in the bodies of animals, and in the clouds; it seems very difficult to reduce all these places to one common matter. Yet this must be necessary, because we do not doubt that the same mixed body according to genus is also generative according to genus. For it is necessary that for all things generated, there be some place of their generation, outside of which they are corrupted and destroyed.

CHAPTER VIII.

Wishing, therefore, to investigate one virtue in all these places, let us recall...