Foresight: looking ahead or looking back

In everyday English, foresight is the ability to anticipate what will happen. It is prudence, planning, the mental act of looking into the future. A business leader praised for foresight has guessed well about market trends. A person acting with foresight prepares for winter before the first frost.

In surveying, foresight has no element of prediction. It is a straight physical observation: a bearing or a distance measured from one survey station to an object located ahead along the line of sight. The surveyor stands at one point and takes a foresight reading to a landmark, a stake, or a natural feature in front of them. This reading forms part of the chain of measurements that map a route or define a boundary. The opposing term is backsight, a measurement taken back towards the previous station or a known reference point.

The reversal is complete. In foresight of the predictive kind you are reasoning forward through time. In surveying foresight you are observing backward through space: you are looking at something that has already been placed or exists, and you are recording its position relative to where you stand.

The metaphor survives because the direction of the observer's gaze is still forward, and because foresight does involve planning, just not of the temporal sort. The surveyor with true foresight, the predictive kind, will have already marked out the stations and placed the targets before setting up the instrument. The naming of the procedure reflects the act itself: you sight forward, even though the data collected is about a fixed present, not an uncertain future.