Why do my / sent text messages appear on the right of the dialogue?

When I read another thread why text messages on the iphone aren't displayed at the full width the following question came to my mind: Why do my text messages appear on the right and not on the left side of the screen?

If I had to design it, it would have been my clear decision to show the messages I'm sending on the left and incoming messages on the right (corresponding to the gestures I would use for sending and receiving). I'd probably have taken this decision without thinking about it at all - just basing on intuition or a gut feeling.

One could argue that the one who started a conversation (or better sent the very first text message), appears on the left. But for the sake of consistency and perceivability, there probably had to be a decision for one of the two options.

Any ideas - or different intuition?