Tsuki means “the moon”; in this chapter Master Dogen uses the moon as a symbol to explain the relationship between an abstract concept and a concrete entity. The moon existed yesterday, it exists today, and it will exist tomorrow. We can say that at one moment in time the moon is a unique and independent entity. At the same time, there is the abstract concept “the moon.” The concept “the moon” is an abstraction of the concrete moon which exists at one moment; that is the moon yesterday, the moon today, the moon tomorrow. Although the unique, concrete moon is the origin of the abstract concept “the moon,” we are prone to discuss philosophical problems only in terms of abstract concepts, forgetting concrete facts, and creating a division between thinking and perception. Buddhist philosophy synthesizes the two factors, and here Master Dogen explains the mutual relationship between thinking and sensory perception comparing the abstract concept “the moon,” with the concrete moon. Secondly, Master Dogen uses the relationship between moon and cloud to explain the relationship between subject and object. Buddhist theory says that reality is oneness between subject and object here and now. Master Dogen explains this using the example of the moon and a cloud that surrounds the moon.