The Sight is a psy technique that works by determining the location of nearby sentient creatures through broad-based Scanning, then picking up their visual thought streams and compositing a picture of the battlefield.
The Sight is not a direct, literal substitute for regular vision. In pitch darkness, where no one can see, there are no visual thought streams to composite and the Sight will do no good. Instead, a separate technique known as Telekinetic Sweeping may be used to directly figure out the shape of one's surroundings.
In rare instances, the Sight can be used to see through time.