This quote is from Strugatsky's novel 'Inhabited Island'.
FSG (Группа свободного поиска) is a label for non-professional space explorers who want to discover new planets and stars. To become a member of FSG one needed mere a piloting license and a flight registration issued by COMCON. After that, one was free to visit the planet he decided to and study it, unless there was a native civilization on it in which case he or she was supposed to leave the planet immediately after destroying all traces of one's presence. Otherwise it can damage the process of civilization's individual evolution.
This job is risky and attractive and is designed for adventurous hotheads.
Serios man would never, never enter Free Search Group.
Author of this face stays unknown.
Put your ray gun to my head!
- Serious grown-up people would not join free search group.