Contemplation of impermanence

The Buddha exhorted us to contemplate the impermanence of conditioned realities. Contemplation of impermanence is not merely thinking about impermanence, it is the direct knowledge of the arising and falling away of a nama or rupa that appears, one ata time. We should realize our ignorance of realities which appear one at a time. We know, for example, that pain does not last, that it falls away. But do we know the realities which are there when we have pain? There are different namas and rupas when we feel pain. The rupa that is hardness may appear, or the nama that is bodily painful feeling, or the nama that is mental unpleasant feeling and that accompanies dosa-mula-citta (citta rooted in aversion) . We are ignorant of the different namas and rupas that arise and fall away when we have pain, we usually think of an idea or concept of pain, we take it for “my pain”. There must be a precise understanding of the difference between nama and rupa before their arising and falling away can be realized. The direct understanding of impermanence is a later stage of insight-knowledge and this stage cannot arise before the first stage of insight-knowledge: the knowledge of the difference between the characteristic of nama and the characteristic of rupa.