The article presents a case study in which a simple, practical observation significantly changed the perception of basic phenomena regarding the mechanism of cell functioning, and thus was able to change the existing theory. This observation drew attention to the fact that the extract obtained from the dry plant substance with the use of pure alcohol, after distilling off the solvent, does not give a dry concentrated extract, and the viscous residue cannot be dried by distillation. This is a phenomenon that practically every phytochemist has encountered since the inception of this field of knowledge. It turned out that the explanation for the described phenomenon is the presence of eutectic solvents. Eutectic solvents are formed by mixing specific solid components, which liquefy without the addition of solvents, thanks to a significant lowering of the melting point of the mixture compared to the melting points of the starting materials. Although more than a hundred years have passed since the description of the above phenomenon, in the field of natural sciences, eutectic solvents have been treated as a curiosity for a long time, while in medical sciences – and more specifically in pharmacy – they were considered an inconvenience causing pharmaceutical incompatibilities. In fact, they are essential for the functioning of cells, enabling plants to develop frost resistance, being responsible for the ability to cryopreserve animal tissues, or allowing the dissolution of substances which are otherwise insoluble inside the cell in either the lipid layer or the aqueous part of the cell juice. The described discovery, made in 2011, allowed for a leap improvement in the understanding of the functioning of living cells.