Those who have practiced meditation may have been told to stop thinking processes while doing the meditation. However, there are also other instructions where the practitioner is encouraged to think, such as thinking about impermanence, rarity of human birth, law of karma, and so on. So how can the two be reconciled? That is, when one is doing meditation the goal is, apparently, to stop thinking, but then there are these instructions where one should be thinking. So what should the practitioner do?
This pertains to the whole topic of Buddhist practice. A short answer is that the purpose of the two kinds of practice are not exactly the same. In encouraging one to think about such topics as impermanence and so on, the goal is to train the mind in such a way that the mind become familiar with these basic and important topics which are the backbone of the Buddhist teaching. How could one gain an appreciation of the need to practice and to release oneself from samsara if one does not fully appreciate impermanence? Impermanence is a key concept in understanding what suffering is all about. So the purpose of such thinking is to engage the mind, to familiarize it, so that it has the habit of thinking along such lines. In other words, we are training the mind so that the mind realizes the truth and fully internalizes it.
One very effective way of training the mind in this respect is to constantly tell the mind about such topics as impermanence, rarity of human birth and so on. One can do this in a meditation setting. That is, one sits cross-legged and puts one’s hands on the lap, and so on. Then one reflects on these topics, aiming at fully understanding them. The terminology for this is “bhavana“, which literally means “to make happen.”
All this naturally involves thinking. So in a way thinking is necessary in meditation. But there is another kind of meditation, which is part of a more advanced practice. In this other kind one is advised to stop the thinking processes. The thinking process is likened to a waterfall, and the aim of the meditator is to stop the waterfall, to clear the mind so that the cascading thought processes stop. The aim is to realize the basic clarity of the mind which will enable the practitioner to see the absolute truth directly.
Now during the meditation should the meditator be thinking? Not if the goal is to stop thinking, of course. But there is a trick. If you are intent on stopping thinking, you won’t succeed because to be conscious of the desire to stop thinking is just another thought process, so you end up traveling in a circle. Instead the trick is to let the mind go and when thoughts arise you are only observing them. Notice when a thought arises and notice when it ends. Meanwhile do not develop another thought about those thoughts. Try to see the gap after a thought ends and before a new thought arises. At first this gap may be very short, but after a while when you are more skillful the gap will widen. This is what the masters have been teaching. Through this gap one can ultimately perceive absolute reality, or in other words Emptiness, or the Primordial Mind, directly.