The use of such images of the impossible is common. Cf. XIV. 37-9, Ex Pont. IV. v. 41-4, Hor. C. I. xxxiii. 7-9, Epod.XVI. 25-34, Virg. Ecl.I. 59-63. Another way of using them may be seen in Virg. Ecl.VIII. 27-8, Hor. C. I. xxix. 10-6, Trist. I. viii. 1-8, where such impossibilities are declared to be possible after the occurrence of some surprising or unnatural event.