In Old Spanish, was used to represent the voiceless palatal sound (as in ' 'he/she said'), while represented the voiced palatal (as in ' 'son'). With the changes of sibilants in the 16th century, the two sounds merged as (later to become velar ), and the letter was chosen for the single resulting phoneme in 1815. This results in some words that originally contained now containing , most easily seen in the case of those with English cognates, such as "ejercicio", "exercise". When Cervantes wrote "Don Quixote" he spelled the name in the old way (and English preserves the ), but modern editions in Spanish spell it with . For the use of in Mexico—and in the name "México" itself—see below.