E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
The motto in the royal arms of Spain. It was once Ne plus ultra, in allusion to the pillars of Hercules, the ne plus ultra of the world; but after the discovery of America, and when Charles V. inherited the crown of Aragon and Castile, with all the vast American possessions, he struck out ne, and assumed the words plus ultra for the national motto, as much as to say Spain and the plus ultra country.