On the Antiquities of Prussia

...a people who are washed by the right side of the Suionic sea, commonly call it Lissom, and he asserts that they collect it themselves among the shoals and other things cast up by the sea on the shore itself, which we see happen even today. Some of our time, being experienced, think it floats from the mud of certain mountains when heated by the sun, and that it hardens in the grassy and cold soil that lies beneath these mountains; when the ocean surges there, it is seized and cast onto the nearby shores. They say evidence of this is that it is sometimes unearthed from solid ground, which we ourselves have seen; because it is of a waxy softness and almost pliable, for that reason they submerge it in the sea again, and by its coldness it turns to stone. I have no intention, however, to either fully support or refute this opinion. The fact that they do not name these mountains makes me suspect uncertainty. Pliny, however, the most faithful interpreter of nature, relying on the experience of the fleets of Germanicus Caesar engaged in war in the northern ocean (as has been said), relates that amber is produced on the islands of the northern ocean, and that it is born from marrow flowing down from trees of the pine kind (just as resin bursts forth in cherry trees, so too does a superabundance of moisture in pines) and is thickened by the coldness of the sea. As the sea swells, it is seized from the islands and cast onto a certain shore, so enveloped in seaweed that it seems to hang from it; it is cast up by the salt sea. As evidence that it is the sap of a tree and that it first distills as a liquid, there are certain things shining inside, such as ants, or bees, or even lizards and other things of that kind, which, there is no doubt, adhered to it while it was fresh, and remained trapped as the moisture hardened. Pine...