How to Investigate the True Nature of the Activities of the Five Aggregates

Pace back and forth in the room while pondering a problem, and identify the activities of the five aggregates at this time, observing them clearly. What is the aggregate of form doing? Where is the aggregate of feeling, and what state is it in? Which one is the aggregate of perception, and what is it perceiving? How does the aggregate of volitional formations operate, and where is the aggregate of volitional formations? What are the object-aspects (nimitta) that each of the six consciousnesses of the aggregate of consciousness discerns?

Then, in meditative concentration (samādhi), slowly and deeply observe and contemplate their nature of arising, ceasing, change, and impermanence, come to know their nature of suffering, and confirm their selflessness.