Hi r/AskHistorians,

I'm looking for the source that would have given PBS the information to write this paragraph:

In fact, slaves looked so similar to Roman citizens that the Senate once considered a plan to make them wear special clothing so that they could be identified at a glance. The idea was rejected because the Senate feared that, if slaves saw how many of them were working in Rome, they might be tempted to join forces and rebel.

Found here: http://www.pbs.org/empires/romans/empire/slaves_freemen.html

If anyone knows where this can be found (Livy? Polybius?) I would greatly appreciate the help.

Thank you!