Horton Smith was the winner of the very first Masters tournament as well as the third. (1934 and 1936). He was also widely recognized as an exceptional putter.

He believed in the Box Principle when it came to holing putts.

“I cannot overstress the value of a consistent and confident attitude toward putting.

You must be positive, decisive, trustful and patient: positive in that you think every putt can be holed; decisive in that you never doubt your plan once you have made up your mind; trustful in that you realize that through learning and practice you have grooved your mechanics; patient in that you recognize that you will make your fair share of putts in relation to your skill, touch and intelligent practice.

As many putts are missed through mental errors as mechanical.

Yet, first, there must be a sound mechanical foundation. This is what can be taught; the rest must be sensed. The basic point of all putting fundamentals is squareness. I call it the "box" principle.

It means simply that the feet, hips, shoulders and hands must all be square to the putting line. The key is the hand position: the back of the left hand and the palm of the right must always face directly toward the hole.

The principle holds true at every stage of the putting stroke. You can achieve the square feeling of the left hand leading the backstroke and the right hand hitting squarely at and through impact only when you have mastered the box principle.”