What is spontaneous generation and why is it important to the history of cell theory?

Spontaneous generation is the belief that there is a form of creation of a living organism that just happens or can occur from an inanimate or dead object. Although disproved, some people still debate it today. The importance of it in relation to the scientific community and cell theory is one that provides guidance for adhering to the most rigid of standards in order to be actually considered scientific and that observation alone is not credible. It could be related to cell theory by suggesting the conversion of one type of cells to another spontaneously, which would be impossible as we now know without the intervention of another living organism like bacteria. The cellular level of these living organisms being incredibly small. 

Organism, organ system, organs, tissue, cells