Which statement from the passage suggests it was written before the twenty-first century?

The first statement highlights logistical challenges regarding large gatherings, specifically mentioning "deliberative assemblies of a thousand members." This suggests a societal structure and political framework that can be associated with earlier centuries, particularly when gathering large groups for political discussions often faced significant constraints due to distance and inadequate infrastructure.

In contrast, modern advancements in communication and transportation have expanded the capacity for larger gatherings and more efficient deliberative processes. The reference to difficulties in accommodating such assemblies implies a historical context where these constraints were more pronounced, suggesting the passage was written in a time prior to the current age's technological advancements.

The other statements, while they reflect on aspects of public influence and the dynamics of crowds, do not inherently contain markers of a historical context that would clearly confine them to a time before the twenty-first century. They could reasonably apply to any era, thus making the first statement the most indicative of a pre-twenty-first-century perspective.