[618] Cicero, Epistle to Atticus, 5.
[619] Ovid, Metamorphoses, b. ii.
[620] This refers to the confused mixture of things, as sung by Virgil:—
“Namque canebat uti magnum per inane coacta
Semina terrarumque animæque marisque fuissent;
Et liquidi simul ignis; ut his exordia primis
Omnia, et ipse tener mundi concreverit orbis.”—
Ecl. vi. 81.
[621] This is always supposed to be the case in vision, the mathematical demonstrations in optics proceeding invariably upon the assumption of this phenomenon.