[neil]

If you're in you address posture the mirror faces you, and is angled off the ground towards you. There is no ball, as it would have to sit on the mirror. A line drawn as if it were the target line could be drawn on the mirror. This represents the plane. If there was a ball, it would sit on this.

The idea is this: we have planes such as the turned shoulder plane, elbow plane and so forth. If it were possible to swing on the eye plane, the club would not appear to curve, but would trace a straight line.

Now imagine a picture of a golfer at setup viewed down the line/towards the target. Draw a straight line from the ball to their eyes. Draw another straight line to represent a selected plane angle. These two lines represent a beam of light reflecting off a surface. A mirror angled perpendicuar to an angle halfway between these two lines can be that surface. Now you can look at the mirror and 'see the [selected] plane' as a single straight line.

Hope this helps,
Chris

Chris you had me very excited there ...but ..how do you see the straight plane line trace unless you are on the "eye" plane.From what I understand from your description ,you will be looking between....lets say the turned shoulder plane and the "eye "plane.From address there is no way you could look along the plane line unless you could get your right forearm along the line of your eyes -and if you did your wrists would be uncocked and.....that is not a procedure .I really wanted that to work ! It would have made all our lives a lot easier