Studying the systematics of lower plants, A.I. Oparin, first of all, became interested in the question of which of them should be considered the most ancient and, possibly, the source for this living. At that time, it was accepted in the scientific world as something beyond doubt that the primary living beings were most likely organisms capable of "extracting" the organic substances they needed by photo- or chemosynthesis. Scientists were convinced that in natural conditions only living beings can create organic substances. True, chemists were already able to synthesize a number of natural organic substances in the laboratory, but this did not at all shake these beliefs. The logic of the reasoning of the supporters of the prevailing view of the origin of the organic world in this case was as follows: a chemist is also a living being, and only he is able to choose the right sequence of reactions for the synthesis of organic substances. In the inorganic world, this does not exist and cannot be. He also believed that it was among the simplest plants, among primitive forms of life, that traces of the original mechanisms of life should be sought, which over billions of years of evolution turned a previously lifeless planet into the cradle of reason. But the biochemical mechanisms of even the most primitive plants turned out to be so complex that it would be the height of optimism to think about the possibility of their occurrence directly from inorganic substances – carbon dioxide, water and nitrogen. And therefore A.I. Oparin suggested that initially much more primitive organisms should have been formed, which were formed from existing organic substances and "fed" on ready-made "organic matter". But in order to justify this, it was necessary to discover possible ways of synthesis of organic substances in inorganic nature. In this regard, D. I. Mendeleev's theory about the inorganic origin of oil helped, as well as the fact that carbohydrates and cyanides were found in meteorites and comet spectra. Ammonia and methane in the atmospheres of large planets were discovered much later, and they strengthened my position already in hindsight.