Crystalline heaven

Use in the book

Aëtius at A51 calls heaven solid, made of air compacted by fire in a crystalline manner. Achilles says it is crystalline and gathered from what is frozen. The scholion on Basil instead calls it water-compacted and likens it to crystalline felting. Lactantius cites Empedocles’ frozen air skeptically beside other possible heavenly materials, such as bronze or glass.

The modern note labels the four reports as agreeing and independent. Their convergence is narrower: several preserve a tradition of solid or frozen heaven, but the air/water difference is real and source independence is not established by this file. Even the tone varies, from doxographic assertion to Lactantius’ refusal to assent.

A54 places the fixed stars bound to the crystal, while planets are released or free. That makes the heavenly material part of a distinction between celestial motions, not merely a metaphor of brilliance. Diogenes’ summary at A1 §77 also describes heaven as crystal-like, giving a further occurrence of the association without settling its physical interpretation.

The appropriate reconstruction is consequently modest: crystalline solidity was attached to Empedocles in several ancient accounts, but the exact material and mechanism must be tracked witness by witness.

Places to read

1. A 51 (testimony)Aëtius II 11,2; Achilles, Isagoge 5. Describes solid, crystalline heaven through compacted air or frozen material.
2. A 51 (testimony)Scholia on Basil. Specifies water-compacted heaven and crystalline felting, differing from the air accounts.
3. A 51 (polemical)Lactantius, De opificio dei. Cites frozen air as a claim he need not immediately accept.
4. A 54 (testimony)Aëtius II 13,11 (D. 342). Makes the crystal the support to which fixed stars are bound.

Translation in this edition

The note’s “four reports, in agreement” conceals the water/air difference, and its assertion of independence exceeds the evidence presented. Diels also records variation in the felting expression.