The Characteristic of Dukkha - The meaning of studying characteristics

Questioner: What is the meaning of studying characteristics?
Sujin: When sati is aware and someone considers the characteristic of whatever appears, that reality can be known as nama, which experiences something, or as rupa which does not experience anything. Then one studies the characteristic of non-self of that reality. It is nama or rupa, non-self. This kind of study is different from thinking about terms or naming realities. When panna is developed to the degree that it is more accomplished, it can penetrate the three general characteristics of nama and rupa: impermanence, dukkha and anatta.
Questioner: When my eyes are open I am seeing, but I do not pay attention to anything else. How can there be sati?
Sujin: We cannot prevent the arising and falling away of cittas which succeed one another, that is their nature. When sati arises it can be aware of whatever reality appears naturally, just as it is.