Here's why:
* Latin was the official language of the Roman Empire: At the time of Honorius' reign, Latin was the language of administration, law, literature, and everyday life for the majority of the Roman population.
* Honorius was born and raised in Rome: It's highly probable that his native language was Latin.
* Historical records indicate Latin usage: While some sources mention that Honorius might have had some knowledge of Greek, there's no evidence suggesting that he was fluent or that he used it in official settings.
Therefore, based on the available evidence, Latin is the most likely language that Honorius spoke.