In my current game I'm in Renaissance era, and have somehow managed to be highest in tech according to demo screen (can't be by much though)...and predictably every Civ is stealing tech like I've left the lab doors open or something. I can't build any anti-spy buildings yet but i have my only spy on counter-spy duty in capital. Something is being stolen practically every turn, although I guess I have the consolation that they will run out of targets soon! Am I failing to employ some well-known strategy here?