We are usually told that for a straight shot the clubface should be square - that is, at right angles to the line-of-aim - at impact, and that it should move down that line.
This is a convenient approximation to the truth. But it is not precisely true. And I have become convinced that the precise truth is the better thought.
The clubface must be exactly square at separation rather than at impact - at the instant the ball leaves it, not when it first strikes the ball.
The clubface collects the ball, which is compressed against it. The two move along together for perhaps three-quarters of an inch before the ball rebounds off the face. It is, so to speak, ''slung'' off the clubface into its trajectory.
If the player can get this feeling - old-timers used to call it ''staying with the ball'' - so much the better. But a lot of people, I am told, cannot. So what are they to do?
The answer is, I feel, ''Think separation.''
Forget about impact. Concentrating on impact makes one hit at the ball rather than, correctly, ''through'' the ball. Think separation instead.
Imagine that the ball stays on the clubface for six inches or so. Try to get the feeling that the clubface is square after impact, not before. After. Long after.
As part of your address routine relate the squareness of the clubface either to the back of your left wrist or the palm of your right hand, and move it ahead of the ball as if rehearsing separation.
I think you will find it becomes much easier to hit through the ball rather than at it.
You'll find the thought ''Square at separation'' invaluable upon the putting green, I promise you.