E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Calpé and Abyla, one at Gibraltar and one at Ceuta, torn asunder by Hercules that the waters of the Atlantic and the Mediterranean Sea might communicate with each other. Macrobius ascribes these pillars to Sesostris (the Egyptian Hercules), and Lucan follows the same tradition.
I will follow you even to the pillars of Hercules. To the end of the world. The ancients supposed that these rocks marked the utmost limits of the habitable globe. (See above, HERCULES PILLARS.)