Concepts II - Can a concept be an object of satipatthana? II

Question: You said that concepts could be known through the mind-door. Therefore, I am inclined to think that if there is awareness through the mind-door, concepts can be the object of satipatthana.
Sujin: In order to have more understanding of satipatthana we should begin with this very moment. Is there a concept while you hear sound now? Sound is a paramattha dhamma. When citta knows the meaning of the sounds it knows a concept and it knows this through the mind-door. Citta thinks about different words. Sati can follow and be aware of that citta, so that it can be realised as just a type of citta that thinks of words.
Question: Thus, satipatthana can know the reality that is thinking, but it cannot know concepts. As far as I understand, each of the sense-door processes has to be followed by a mind-door process, it cannot be otherwise. When there is seeing there is an eye- door process, and after there have been bhavanga-cittas in between, there is a mind-door process of cittas which experience visible object. Is that right?
Sujin: The víthi-cittas of the mind-door process, which follow víthi-cittas of a sense-door process, have to experience the same rupa. If the javana-cittas of the sense-door process are lobha-mula-cittas (cittas rooted in attachment), the javana-cittas of the first mind-door process after that sense-door process have to be the same types of lobha-mula-citta. The mind-door process follows extremely rapidly upon the sense-door process. With respect to this there is a simile of a bird perching on a branch. As soon as the bird perches on the branch its shadow appears on the ground. Even so, when the object has been experienced through the sense-door and there have been many bhavanga-cittas in between, arising and falling away very rapidly, it is immediately afterwards experienced through the mind-door. Since cittas succeed one another so rapidly one does not know that visible object which is experienced through the eyes is only a paramattha dhamma that can appear because it has impinged on the eyesense.