The history of computers seems somewhat pervasive since there are so many steps in modern manufacturing and so many changes in trends with transistors over many years. Grasping how we got to our current level of processing power seems somewhat like a chicken/egg situation. How exactly were we able to create such precise processors when we only could have had more primitive tools to craft them with? For instance, take the UV stencil used on a silicon wafer to make a CPU.

How could engineers have designed a machine capable of cutting out so many millions of transistors in the stencil given that they didn't originally have access to that level of processing that they are trying to achieve? Or in other words, how is it possible for computers to evolve in the process of making more precise machines from less precise machines?