There are various mental activities we can call thinking, but let us say that this term applies only to some out of such activities and not to others. What is the the most typical of these? To extract a course of action from a state of affairs; to work out what to do in a wholly or partially novel situation. This is little distinguished from purposive action and is seen in all life, including in creatures with little or no nervous system. Let us add the reflexive twist that the state of affairs must be sufficiently complex that thought and its products are present in it as objective elements. For example, where the situation is such as responds to one's own purposeful interventions. This still includes much animal activity, but the situations are now puzzle-like and the responses even of animals deserve to be named thinking.  It describes a high-level activity, considered purely as process, one which needs to call upon a range of subsidiary knowledges which are themselves the products of earlier thinking, but it is for the most part, and in the intended sense, immediate and unreflexive. Again, the move to action may be suspended, or deferred, so that I seek to understand a situation in order that the understanding be available to contribute to a future decision cycle. Though initially geared to action, thought may thus assume a contemplative air. The sense of coming up directly face to face with some thing or situation is not thought, but thought may be used to bring this about, or to prevent such a feeling arising when it is not justified. I can't think or deliberate about a challenging situation until I have grasped it as clearly as possible, and such a grasping is not itself thought; thought is a means to it, perhaps a very precise means of eliciting and incorporating such a grasping, or better, presencing of a goings on. The latter is closer to the sense of witnessing, and is not, and could not usefully be, a product of thought.