This subject of this book is also subjects, i.e. it is subject of the subjects. Several library scientists views about subjects are analyzed here. The characteristics of the subjects are analyzed through uncontrolled vocabularies, i.e. author-assigned keywords. The keywords may be reckoned as fundamental quanta to describe the content of a subject or topic. From the viewpoint of chemistry, the keywords may be looked upon as molecule of a subject topic. As the molecular theory of matter interprets microscopic state, the subjects are also described here from microscopic viewpoints when...