Similarly, the ear with sounds, is the form-aggregate. and the consciousness which arises from them is the mind-aggregate. The mind and Form (Nama-Rupa), having arisen, then die away and cease.

As for thoughts which are memories of the past, they arise from the perception of mental sensations (Nama-Dhamma). In other words, what was-seen and heard in the past was retained and this gives rise to thoughts of the past. Things which were not seen and heard, such as other towns, countries, and so on, with which we are not familiar; or forms of knowledge which we have never known, cannot arise in thoughts, for we can only think of that which we have known.
When one sees one's body and mind to be other than one's self, then examining all things and seeing that they are not one's self is insight (Vipassana) with searching thought.2