Like pooping, spitting up, crying for no apparent reason whatsoever, spitting up some more, smacking their food on their high chair tray instead of eating it, giggling at random things (like my wife's feet...really, can you not see that far, Mason), and breathing, all kids do it and it is as expected as the sun coming up in the East (albeit not always bright and sun-shiny-like), but when you own kid does it that first time, it sort of blows your mind. Perhaps it is that they are doing something uniquely new to them. Perhaps it is that you are getting to witness the complete development of a child, where you can look back ten years down the road and think, "oh, i know why he is like that, it is because of x, y, or z."
Regardless, when I watch Mason learn to go from his stomach to his back to sitting and now to crawling (albeit a few steps), it is sort of like watching Lance win his 7th Tour de France, or Team USA defeating the Russians in 1980 (even if it took another game to win the gold), or a person flying through the air without aid. And you know, it doesn't really get old. I keep watching it, over and over. And over again.