A more thorough explanation:

Definition: Libellos agere is a Latin term used in Roman law which means to assist the emperor in responding to petitions. It is also known as libellum agere.

Example: In ancient Rome, citizens could submit petitions to the emperor for various reasons such as requesting a pardon or seeking justice. The emperor would then assign officials to assist him in responding to these petitions. These officials were said to be "libellos agere" or "libellum agere."

Explanation: The example illustrates how the term "libellos agere" was used in ancient Rome to describe the process of assisting the emperor in responding to petitions. It was an important role that helped ensure that the emperor was able to address the concerns of his citizens and maintain order in the empire.