...there are some sceptical persons who may think that when the mind is not moved by many thoughts, it will be in a stupid state. But stupidity does not arise just because the mind relaxes a little. On the contrary, the mind usually thinks too much. We are used to thinking uninterruptedly and continuously. If we look at these thoughts more closely, however, we discover that we seldom think meaningfully at all, and that most of our thinking is rather senseless. Such senseless thinking happens frequently and repeats itself over and over. In this way our many endlessly occurring thoughts are continuously going around and around in circles.
If we are able to decrease this senseless thinking, meaningful thoughts will naturally increase all by themselves. And this is exactly the reason for the meditation on calm abiding: when the mind relaxes, senseless thinking will effortlessly diminish.
-from Everyday Consciousness and Primordial Awareness, by Khenchen Thrangu Rinpoche