The chapters in this book explore the notions of interior and exterior and their importance in various branches of modern science. To begin with, a basic description, quoted from the French philosopher Bachelard, can be found in an essay published by the Japanese philosopher Izutsu in 1975 ([1], p. 588):"It would seem that the distinction between the interior and exterior is a kind of intrinsic geometry of the human mind. As Gaston Bachelard [2] once remarked, "the dialectics of outside and inside" belongs to the most elementary and primitive stratum of our mind It is a deep-rooted habit of our thinking. In fact we find everywhere the opposition of the interior and exterior. "Inside the house" versus "outside the house", "inside the country" versus "outside the country", "inside the earth" versus "outside the earth", "inner (i.e., esoteric) meaning" versus "outer (i.e., exoteric) meaning", the ego or mind as our "inside" versus the external world as our "outside", etc. etc. The everyday ontology reposing upon the contrasting geometrical images of the interior and the exterior thus forms one of the most fundamental patterns of thinking, by which our daily life is largely determined "It (i.e., the dialectics of inside and outside) has", so says Bachelard, "the sharpness of the dialectics of yes and no, which decides everything. Unless one is careful, it is made into a basis of images that govern all thoughts of positive and negative.""