There is a certain degree of difficulty in any investigation of the mind, since it is an entity, unlike the body, that cannot be seen or touched. The body is the first of the aggregates explained in the sutras because it represents external and substantial matter; consciousness, on the other hand, is placed at the end because it pertains to mental phenomena which are the most difficult to examine.

For most of us, the best way to investigate the mind is to analyze it in relation to time.

- Quote from The Four Seals of Dhama, "All Phenomena Lack Self-Existence"