Isaiah 45:19

I have not spoken tn secret, in a dark place of the earth - In opposition to the manner in which the heathen oracles gave their answers, which were generally delivered from some deep and obscure cavern. Such was the seat of the Cumean Sybil: -

Excisum Euboicae latus ingens rupis in antrum .

Virg. Aen. 6:42.