The Stages of Vipassana - 4th stage of vipassana nana

The fourth vipassana nana is knowledge of the arising and falling away of nama and rupa (udayabbaya nana).  
Vipassana nana of the third stage realises the rapid succession of namas and rupas as they arise and fall. However, at this stage panna is not yet keen enough to see the danger and disadvantages of the arising and falling away, so that there can be detachment from them. The immediate arising of a new dhamma after the falling away of the former dhamma covers up the danger of the arising and falling away. Panna should become keener so that the following stages of insight can be reached. At the fourth stage panna can penetrate more clearly the arising and falling away of each kind of nama and each kind of rupa separately. One should not try to do something else but should continue to consider the characteristics of nama and rupa. One should be steadfast in the development of panna.
All kinds of nama and rupa can be object of understanding, no matter whether they are kusala dhammas or akusala dhammas, no matter of what degree of kusala or akusala they are or through which doorway they appear. The fourth stage of vipassana nana (udayabbaya nana) knows more precisely the arising and falling away of each kind of nama and of rupa as it appears one at a time. This stage of insight can arise when “full understanding of investigation" (tirana parinna) has become more   accomplished. The full understanding of investigation is the kind of panna that considers and clearly understands the characteristics of all kinds of nama and rupa as they appear through the six doors. So long as this is not the case, there are no conditions for the arising of udayabbaya nana.
The person who develops the right Path knows that nibbana, the reality that eradicates defilements, cannot be realised if understanding of conditioned realities has not been fully developed. First, the panna should be developed which clearly understands the characteristics of nama and rupa as they naturally appear in daily life. It is impossible to realise nibbana if panna does not penetrate thoroughly and precisely the characteristics of all kinds of nama and rupa that appear through the six doors. 
The characteristics of nama and rupa that appear through each of the six doorways are different from each other. If panna does not precisely understand the difference between the characteristics of nama and rupa as they appear through the six doorways, the arising and falling away of nama and rupa cannot be realised. Then, ignorance, doubt and wrong view about realities cannot be eradicated.