The development of the electron microscope was hotly debated because it claimed to circumvent a physical boundary that for decades had been considered to hinder the further exploration of the microstructures of organic and inorganic bodies, or even make it impossible. Over a period of several centuries, geometric optics had served as the basis for calculating the paths taken by light in optical systems. It had given satisfactory answers to questions of image formation and provided technical solutions for certain problems of microscopic practice. But instruments that worked with optical systems consisting of several lenses, in particular, were considered unreliable due to imaging artifacts that distorted the image in some way, and the results were considered untrustworthy from a scientific standpoint. In the course of the nineteenth century, chromatic aberrationAberrationschromatic aberration, which produces colored fringes around image contours, was largely corrected by combining lenses of different shapes made from different materials; and likewise later forAberrationsspherical aberration spherical aberration.