The first [of the Five Aggregates] is the Aggregate of Matter (Rūpakkhandha). In this term ‘Aggregate of Matter’ are included the traditional Four Great Elements (cattāri mahābhūtāni), namely, solidity, fluidity, heat and motion, and also the Derivatives (upādāya-ripa) of the Four Great Elements. In the term ‘Derivatives of Four Great Elements’ are included our five material sense-organs, i.e., the faculties of eye, ear, nose, tongue, and body, and their corresponding objects in the external world, i.e., visible form, sound, odor, taste, and tangible things, and also some thoughts or ideas or conceptions which are in the sphere of mind-objects (dharmāyatana). Thus the whole realm of matter, both internal and external, is included in the Aggregate of Matter.