I am using a square instead of rectangle because a rectangle can have two sides of one length and the other two sides of another length. (Of course, a square is a rectangle, but a rectangle is not necessarily a square.)
So, each side of a square is the same length and all four sides are needed to make a perfect square. So it is with meaning and happiness. There are two opposite sides of our square; one of those sides has the words “inside-happiness” and the other, opposite side, has the words “outside-happiness.” Then, of course, there are two more sides of the square. They are opposite each other as well. Those two sides carry the words meaning-inside and meaning-outside, respectively.