Here's why:
* Hebrew: Solomon was born into a Jewish family in Poland, where Hebrew was the liturgical language of the community. He likely learned it from childhood.
* Yiddish: Yiddish was the everyday language of Ashkenazi Jewish communities in Eastern Europe, making it highly probable that Solomon was also proficient in it.
* German: German was the official language of the Prussian monarchy, where Solomon lived before emigrating to America.
It's also possible he had some proficiency in English after settling in America.
However, without concrete evidence, these are just educated guesses based on his background and the languages prevalent in his communities.