My thinking mind as subject of my meditation stops my thinking

Just recently I changed my subject of meditation: I try to "watch" my mind while it is thinking. This nearly instantaneously makes my mind calm. It kind of stops my thinking. And this feels great. It's also easier to come back to this state, once my mind starts to wander around. I use this occasions to watch my mind as well. [There is in principle an infinite regression (I could also watch my mind, watching my mind thinking), but I never came to make use of that.] Is there some more guidance in the buddhistic literature or stuff that support this kind of meditation? Is there a name of this mental state?