The identity of a culture is oftentimes reflected in the respective language. This makes learning a language integral for understanding the culture. Additionally, learning the language enables you to read the original sources and to create your own interpretation of them independent from the influences of original translators.
When your field of study is an ancient culture, you most certainly will have the problem that the ancient language isn't consistent with its modern equivalent or isn't even spoken any more at all. This makes learning, apart from an university course, so much more difficult, but luckily there are persons sharing their knowledge with others.