PL 83, col. 209C
'And the Spirit of God was borne over the waters.' The Spirit of God was already being borne over our dark and fluid heart, as over waters: that standing in him we might find rest, be quickened by his breath, and be washed in his wave.
Fresh draft (Claude), approved by Wilson Pruitt · cc-by
PL 83, col. 209C · pd
Isidore does not answer the physical question at all; the waters are the heart. The allegorical reading the Glossa will carry in its margin.