You cannot switch the position of two things occupying space in two steps. It's always done in three steps, unless you do it simultaneously. But, I'm not talking multi-threads here. I'm talking about linear execution of events.
To switch the places of two blocks, you will have to first move the first block to some place to free the space that the other block will be occupying. Then, you will move the other block to the position that the first block had just vacated. Then, you'll go to the first block to fill in the other block's old position. It's a trade.
This kind of behaviour happens most of the time with computers. You cannot co-change the positions, or move them simultaneously. You only have one controller, and you can only do one command at the time. All of the simultaneous activities done by the computer are only done in the background. Most of the time, too, if not always, the user isn't the one who give out these commands to the computer. But, some of the latest computers of today, especially "Microsoft Surface", and an American invention, "The 6th Sense".
I wrote this entry not because I want to talk about technology. I only used it as an analogy that I saw with the way of life. In order to gain something, you'll have to lose something. In order for you to accomodate something in your heart to love, you'll have to let go of something else first. That may be hang-ups, an old love, your past, and so on; even a combination of any or all of them. Also, in order for you to get someone, there may be times that you'll need to let go of your loved ones. You'll have to take risks. You'll have to sacrifice. You'll have to leave everything behind even. That is what I'm talking about right now.
Well, it's funny cos I realized this while playing Backyard Monsters on Facebook. I was switching some blocks around and I was annoyed at how switching the places of two small blocks can be so complicated. I felt like "this is how life is -- you'll have to let go to get something back". I also then tried to ponder more on that thought, and I remembered about multi-threading in program execution -- yeah, I know, computer programming jargons; me has a habit of mixing life and how it works with the things I'm currently working on such as computers, art, whatever I'm doing.
So there. I just want to reflect on the concept of "exchange". Something for nothing? Not quite. Something for something else, I guess. Give to gain. That's it.
Oh. And happy new year! :)