The artwork created by a civilization visualizes the identity of that culture. As the artwork spreads into other civilizations it gives increased influence over that civilization.
Food is a great way to spread culture, and the more you spread your culture, the more influence you gain. Eventually your influence will turn into jurisdiction and control.
Interstellar Broadcast System
The Interstellar Broadcast System helps you spread your culture to other stars, increasing your influence and power.
Music runs deep into the sub-conscious mind and can exert great influence over those that it affects.