References
Videos for further exploration
This video describes different communication technologies used in Ancient Greece
What would the life of an ancient Athenian be like?
Links for further learning
Aeneas Tacticus
Aeneas Tacticus describes, in his book, How to Survive Under Siege, different methods for sending secret messages.
Hydraulic Telegraph, Scytale, and Polybius Square
To transmit messages over long distances, the Greeks used the Hydraulic_telegraph.
https://en.wikipedia.org/wiki/Scytale
The Scytale: An Early Greek Cryptographic Device.
https://en.wikipedia.org/wiki/Polybius_square
The Polybius square is a device invented by ancient Greeks and made famous by the historian and scholar Polybius.
Tap code (or The Polybius Square) in Vietnam War
Literacy in Ancient Greece
William V. Harris. Ancient Literacy https://www.amazon.com/gp/product/0674033817/ref=dbs_a_def_rwt_bibl_vppi_i4
D. Harvey. Literacy in the Athenian Democracy https://www.persee.fr/doc/reg_0035-2039_1966_num_79_376_3884