Theophrastus examines exposed earth on a hillside.

Where the story of a stone begins

Theophrastus of Eresus (c. 371–c. 287 BCE) was a Greek philosopher and natural historian. A reader opening his work On Stones might expect to meet a colour, a name or a description of a quarry. The first sentence begins earlier in the story. Theophrastus asks what the things eventually found underground came from. That order of questions determines what an individual specimen can tell us in the pages that follow.

The first question in the book on stones

Of Things formed in the Ground, some have their Origin from Water, others from Earth. Water is the Basis of Metals; as Silver, Gold, and the rest: Earth of Stones; as well the more precious, as the common […].

– Theophrastus of Eresus, On Stones, 1774, p. 3–5.[1]

Two pieces may come out of the same pit and occupy different places in his account. The ground is, in the first instance, where both were found. In considering their origins he distinguishes earth and water. He goes on to associate fusible metals with one origin and stones with the other. This gives an ordinary observation considerable weight. What happens when a specimen is exposed to heat? Its behaviour under those conditions may say more about its relations within the scheme than its appearance does at first sight.

From a find to an explanation

A person picking up a stone today can still follow the movement of the question, even though the ancient explanation belongs to a different understanding of matter. One knows where the piece lay, sees its colour and feels its weight. Its formation is another matter. Theophrastus opens his book in precisely that space between an available surface and a past event. He gives the descriptions that follow a shared purpose. With each new quality one can ask whether anything about the becoming of the stone has come into view.