This chapter outlines key issues which have arisen as strategists rediscover intelligence. It discusses how theorists have depicted the relationship between intelligence and strategy and how their work may help policymakers organise intelligence services to keep strategists as well informed as possible. The chapter shows that intelligence agencies perform functions that go beyond passively gathering information. It focuses on intelligence operations in the physical world. Spies, scouts, cryptographers, cryptanalysts, military cartographers, and other intelligence practitioners have been active in every historical era. Strategic thinkers, however, have not always fully appreciated their uses. The intelligence cycle is a concept that summarises the steps that intelligence agencies must take to provide strategists with enabling information. Collection is most dramatic part of the intelligence cycle. It can also be the most dangerous and expensive. Some might be willing to sacrifice their jobs for their principles, but they will never purge intelligence of politics. In intelligence work, the full truth is almost never obvious.