What is the relation between aircraft stability and control?
You are right.

Stability is the tendency of a system to return to its old state after a disturbance, be it a gust or a control input. It needs more control effort to change the state of a more stable airplane, such that stability can be measured by measuring control forces instead.

A famous example which is often mentioned in literature is the BE.2, a British two-seater which was designed as a training aircraft in 1912. As a trainer, it had ample stability, so its control responses were sluggish. That proved to be its undoing when war broke out in 1914. The BE.2 was easily outmaneuvered by dedicated fighters, so it had to be withdrawn from frontline service.

Quote from Wikipedia:


  While it proved fundamentally unsuited to air-to-air combat it had a
  relatively low accident rate, and its high degree of inherent
  stability actually proved helpful in its artillery observation and
  aerial photography duties (although it also made it more difficult to
  maneuver quickly)




BE.2 (picture source)