I would like to apologize to write this manuscript alongside my own prejudice. Naturalsciences consist of physics, chemistry and biology, which deal with "substances". In physics, atoms (or simple molecules) are the main subjects to study, while in chemistry the molecules and in biology the substances (biomaterials) are treated. There are only about loo atoms among which 92 elements (92U) are the naturally produced atoms, therefore research objects in the physics are quite simple and clear. Since in the chemistry molecules play important roles particularly, in the case of organic chemistry more than 10 millions molecules are known in the world. Materials in the world are composed of the molecules and hence the chemistry needs quite different methodology from that employed in the physics. There are three fields in the chemistry, namely reaction chemistry, structural chemistry, and synthetic chemistry. In order to produce the materials, it should be understood the structures of the starting molecules to be composed. As meanings for structural determination of the molecules, recently many spectroscopic methods such as NMR, Mass, IR and UV are used to understand the structures and chemical behaviors of the molecules in the solution. At the same time, due to the remarkable progress in X-ray crysta11ographic analysis, a number of molecular structures have been identified precisely and its development has contributed much to the progress for investigation of the chemical reactions. It is the dream for the chemists to watch visually the chemical reactions. The development of the analytical methods using instrumentation can realize this dream. In the recent field in the chemistry, the synthetic chemistry on the basis of reaction chemistry and structural chernistry is the mostly developed field and chemists have self-confidence to synthesize any kind of compounds. Particularly, the combinatorial chemistry has been received widely to synthesize several hundreds molecules at once using a computer regulated synthetic apparatus. Biology has become quite popular to organic chemistry since the term "molecular biology" has been used and in the near future it becomes possible to demonstrate the biological phenomena (reactions) in terms of molecules. Since the biological phenomena are roughly considered to be the reactions involving organic molecules, the biological phenomena should provide a new field, i.e., "reaction biology". Therefore, the structures of the biological substances should be required to determine. In view of the chemists, it is still ambiguous structures of the substance, which have generally been used by the molecular biologists. At this time, Professor Sakabe has tried to determine precisely the complex structures of proteins by photo,radiation crysta11ography. In the future, it is naturally considered to be determined even both the fine structures such as configurations and the dynamic changes of the biochemical substances. It may not be the future dream to born "reaction biology" and "synthetic biology". I have much expected to the development of "structural biology" by Prof.Sakabe's group.