Two bulls in Mars's field your wonder claim,
Their hoofs of brass, their nostrils breathing flame.
These oft I seize, and to the yoke constrain
To plough four acres of the stubborn plain.
No seeds I sow, but scatter o'er the land
A dragon's teeth; when, lo! an armed band
Of chiefs spring up: but soon as they appear,
I slay th' embattled squadrons with my spear.
Each morn I yoke the bulls, at eve resign:
Perform this labour, and the fleece is thine.

Lines 446–455; Aeëtes' challenge to Jason. - Argonautica (3rd century BC) - Book III