Why did the law of spontaneous generation survive for so many years

The law of spontaneous generation states that the living forms can grow from the non-living objects. The examples of this law were believed to be the arrival of maggots on meat, and dust from the flies. This law was believed to be true for an extended period of time. During those times, the microscope was not invented, and hence, people were unaware about the existence of the living organisms that cannot be seen with the naked eyes (microorganisms). This led to the people believe in the spontaneous appearances of life forms.