“Where there's smoke, there's fire.”
Smoke works best when you inhale it, and less well when it gets in your eyes.
Some people say there is no smoke without a fire. This is most easily observed in practice by the smoke pouring out of the ears of someone who has been unexpectedly fired. Scientists worldwide were working around the clock without breaks to falsify this statement, but most have now been fired - many are sitting at home at this very moment, smoking up.
Other situations where smoke has been found without a fire are the many instances that smoke has been on the water. How it got on the water? Nobody knows for sure but there are some theories out there. Such as underwater fireworks, alien invasion one piece of water at a time or simply Jimi hendrix's bong.
Smoke is also known by the Fearnots and the Masons to be the ethereal element that makes things work. Hence the phrase "I let the smoke out of it." Meaning: the device in question stopped working. This is most evident in internal combustion engines, computer power supplies, toasters, and vacuums. As you study the innards of the power supply and many other electronic devices, you will notice small colored cylindrical pieces soldered to the various electronic boards. These are filled with smokes of different colors and weights. It stands to reason, the more catastrophic the failure, the more smoke will be released. An old rule of thumb is: before testing the used part, smell it, if it smells like smoke, it probably doesn't have any left. For a more in-depth study of this fascinating phenomenon, you can get the free guided tour of the many smoke plants just outside Winston-Salem, VA.