King Solomon's Square - A Problem of Probability

King Solomon was once presented with 4 boxes by the King of Egypt.
"2 of the boxes contain gold and two are empty", said the Egyptian king, "You may pick 2 of the boxes but you must pick at least one box that has gold in it".
Stroking his beard, King Solomon considered the boxes and then, after considering them for some time  he thought to himself,
"Say that the boxes are like this; full, empty, full, empty, then if I placed the first two boxes ontop of the second ones it would form a square in which the two boxes on the right were full but then say the boxes are like this; empty, full, empty, full, then if I placed the first two boxes ontop of the second ones it would form a square in which the two boxes on the left were full but then what if the boxes are like this; full, full, empty, empty, then if I placed the first two boxes ontop of the second ones it would form a square in which the two boxes on the top were full and if the boxes are like this; empty, empty, full, full, then if I placed the first two boxes ontop of the second ones it would form a square in which the two boxes on the bottom were full. In three out of these four scenarios, top, bottom and right there would be gold in at least one of the boxes on the right so if I place the first two boxes ontop of the second two forming a square and pick the two boxes on the right side of the square then I have 3 out of 4 chances that one of the boxes will contain gold".
So that is what King Solomon did and, fortunately, the gold was in the first two boxes so King Solomon won the King of Egypts challenge.

Note: I forgot to mention two other possibilities, that the boxes are empty, full, full, empty  or full, empty, empty, full  but in both these scenarios there would still have been gold in one of the right boxes of the square so Solomon would have instead of 3 out of 4 chances have had 5 out of 6 chances of picking a box with gold in it which is still great odds.