Over the years, technical innovation in the physics of electrophotography has had mixed results in influencing the technology. Four examples familiar to the author will be discussed and their current and potential future influences on the electrophotographic technology will be described. (1) The introduction of the theory of magnetic brush development had only limited influence on the invention of improved variants. However, it had an enormous influence on the perception that electrophotography was a logical and predictable technology that could be understood with common scientific tools. (2) The introduction and implementation of the ideas of the proximity theory of toner adhesion has allowed the design of the smallest size lowest cost color electrophotographic engine which will be commercially available soon. (3) The demonstration that toner charging is due to Kondo's high density theory surprisingly has failed to help toner material scientists redesign toners; in particular, it has failed to help them design a toner with a narrower charge distribution. Such a narrow-charge distribution toner would allow the average toner charge-to-mass ratio to be reduced, which would be useful in many of the electrophotographic subsystems. Combining a narrow-charge distribution toner with the methods of reducing the toner adhesion based on the proximity theory could lead to a new generation of marking engines based on novel marking technologies. Finally, (4) progress has been made recently in identifying the mechanism by which holes move through photoreceptors. The author conjectures that elucidation of the charge transport mechanism will be beneficial to the design of organic photoreceptors for electrophotographic systems as well as other organic electronic devices. Although today's photoreceptors have adequate mobility, increased process speed will require both higher mobility and a reduction in those factors giving rise to carrier range limitations. For organic electronics higher mobility materials are necessary for practical devices.