Conversation so far:
Who was Voltaire?
Voltaire was a French Enlightenment writer, historian, and philosopher famous for his wit, his criticism of Christianity,
Are there any other interesting aspects about Rousseau's time with Voltaire and Frederick the Great besides who Voltaire was?
After Rousseau's Emile had outraged the French parliament, an arrest order was issued by parliament against him, causing him to flee to Switzerland.
Was Jean-Jacques Rousseau arrested in Switzerland?
Rousseau was informed that he could not continue to reside in Bern
What happened after Jean-Jacques Rousseau was driven from Bern, Switzerland?
d'Alembert advised him to move to the Principality of Neuchâtel, ruled by Frederick the Great of Prussia. Subsequently, Rousseau accepted an invitation to reside in Môtiers, fifteen miles from Neuchâtel
What did Jean-Jacques Rousseau do in Motiers?
Rousseau, touched by the help he received from Frederick, stated that from then onwards he took a keen interest in Frederick's activities.

Question: What types of activities?
Self-contained rewrite: What types of activities?