After the collapse of the Roman Empire, Western Europe experienced a general decline, including a decline in technology. However, the basic needs of the population required the continuation of certain activities. In addition, the advent of new products such as horseshoes and heavy armor for knights facilitated the advancement of metallurgy. Thus, the decline in technology did not affect all sectors equally. It seems reasonable to agree that medieval technology allowed the decline of what was no longer interesting and concentrated on the gradual development of what met not only material needs but also common sentiments in accordance with the new culture. The process of adapting technology to the new situation was clearly a long one, during which the Europeans rediscovered many techniques from the Romans and acquired others from outside sources, often improving upon them. The most significant technological advance of the Middle Ages was the advent of mechanization. The term “mechanization” is used here to describe the use of machines to replace human labor. The water wheel was the basic instrument of mechanization. The main characteristics of water wheels are their high power output and continuous rotation. The latter characteristic requires a method to convert the continuous rotation into the alternating motion required by a variety of devices. In medieval technology, the answer was the camshaft. The combination of water wheel and camshaft was a successful mechanization solution for many centuries and played a fundamental role in the industrial development of Europe.