Medicine began as an art form. Practitioners applied various herbs and curing processes based upon knowledge handed down, often in secret, from generation to generation. Medicine as a field did not really progress, until various forms of learning, based upon experimentation and model building, took place. Learning from the application of medications and procedures formed a base for evolving our knowledge of the relationship between these solutions and their effects. Experimentation takes on many forms, from controlled experiments to case studies. Depending on the area of interest data may be hard to acquire. However, our knowledge of the human body has evolved over time. But both grew based upon our understanding of the relationship between the procedures (processes) and its effects on the body (product). The medical practitioner can and does manipulate the body, but the essence of the body, which is physical, does not change. Again, the understanding was based upon model building, experimentation and learning.