Isidore examines a piece of amber beside a pine.

How Isidore traces amber back to a tree

Isidore of Seville (c. 560–636), a scholar and bishop in Visigothic Spain, gives amber a place among the precious materials in his encyclopedia. A piece of amber can be picked up and examined much like a stone. When Isidore asks where it came from, however, the enquiry leads him back to a tree. The material held in the hand must once have been soft enough to flow.

A name that points to a tree

It is established, however, that it is the sap of the pine rather than the poplar, for when lit it gives off the scent of resinous pinewood. It forms like gum on the islands of the northern ocean and, like crystal, grows dense through cold or time.

– Isidore of Seville, Etymologiae, 1911, XVI, 8, 6–7.[1]

Isidore associates the Latin name sucinum with the sap of a tree. For him the word gives a clue to an earlier stage of the material. Its solid shape alone would offer little hint of that origin. The comparison with crystal helps his reader picture a transition. Something firm to the touch can have a fluid beginning in the account of how it came into being. Cold and the passage of time are among the explanations he records.

Which tree does the evidence suggest?

Isidore gives his reader a way to choose between poplar and pine using the amber itself. In the poets’ account the tears of Phaethon’s sisters, who turn into poplars, seem to point to the poplar. Set the amber alight, however, and the smell recalls burning pinewood. It is the nose that decides in favour of the pine. Isidore then describes another property. Rub amber between the fingers and it draws leaves and straw towards it. The hand that might take the hard material for a stone can thus make it disclose something its appearance could never have told the observer.