The Pillow Mystery

My wife uses a flatter and harder pillow, while I use a more fuller and softer one. Clearly indicating that I am the more indulgent one! But a mysterious thing kept happening with me. At bedtime, when I would retire I would see the flatter pillow on my side of bed while the fatter one on her side. I would switch the pillows and sleep. In case she had slept before me, I would snatch it from below her head. However, the next day the pillows would be swapped again when I would hit the bed. Knowing well, that my wife doesn't have a preference for any pillow, I would think that she took it inadvertently. It was possible as the pillow covers would always be the same, again, as per my wife's designs. I asked her one evening whether she had changed the pillows as they are not known to shift spontaneously, she simply said, "What's the difference?", without even thinking about it as an issue. I kept wondering that how the pillow that was left on right in the morning had left for the left by evening, something was not right!Then I got it! My children must be playing prank on me. At this age they do love these kinds of mischief. In a disguised manner, I inquired the matter, without giving them another fodder for a prank, were they not already at it. Asking a leading question would not have elicited a trustworthy response either. I gauged that probably it was not their handy-work. I decided to do a longitudinal observational study. Without fail, it kept occurring every day. For everybody else, it was not a matter of any concern but my curiosity kept growing. Then I thought of an interventional design. After getting up in the morning, I switched the pillows and kept the flatter one on my side and the fuller one on her side. Lo behold! They were again switched by evening and this time the fuller one was on  my side. My intervention had worked but I became more inquisitive! Next day was a Sunday and we were home. During the daytime, while I was busy with some of my paperwork, the mystery was solved. Our house-help came and I noticed her making the bed. She lifted the pillow on right, straightened it out, kept it on left and picked up the left one and placed it on right. She did so with the folded sheets also, but since they were exactly the same, it didn't make a difference. I called my wife and told her about the unraveling of the mystery. We had a hearty laugh. I asked our help that why she was switching the pillows? She counter-questioned, 'Are they different?' All burst out laughing at my finickiness.