A palm leaf on a broken stone

Pliny the Elder (23/24–79 CE), a Roman writer and naval commander, brings together some remarkable observations about rocks in the thirty-sixth book of his Natural History. One of them takes him to the neighbourhood of Munda in Spain. Break open a stone from that district, he reports, and a pattern may appear on the fresh surface. Its outline can be described by naming a single familiar part of a plant.

What the fracture reveals

In the vicinity of Munda in Spain, the place where the Dictator Caesar defeated Pompeius, there are stones found, which, when broken asunder, bear the impression of palm leaves.

– Pliny the Elder, Natural History, 1857, p. 358.^[1]

It is easy to miss the small interval between breaking and recognizing. From the outside the observer could have had little idea of what was about to come to light. Only when one piece becomes two does a previously inaccessible surface face the light. The eye then needs a comparison. The axis of a palm leaf and the narrow divisions to either side give it a pattern recognizable even from a few strokes.

How literal is the impression?

Pliny gives a place and an appearance. He does not say whether an actual leaf once lay between the layers or explain how this particular rock formed. His choice of a word for an image is therefore important. It tells a reader what to look for while leaving the origin open. The same passage mentions bones and ivory reportedly found in the ground. Set side by side, the observations show how much the naming of a find depends on a trained eye. A familiar leaf becomes an instrument of description even when the author can put neither the specimen nor the leaf into a reader’s hand.