I read the civilopedia and played one game of BTS and I haven't really had a problem understanding it.nobody except firaxis knows about spies
and they ain't talking
this confusion is a shambles
Just assign 10% of your output to espionage starting around, oh, say, Philosophy, and if in later ages you can see all the other civ's cities, go ahead and turn it off. Use the Espionage screen if you want to allocate your espionage unevenly.
represents the resources necessary to insert an agent, keep them safe, and pull off the mission.