In 1620, during a period of time known as the Scientific Revolution, Sir Francis Bacon helped develop a method of testing the truthfulness in knowledge. This method involved testing hypotheses by manipulating nature in an effort to rule out faulty knowledge garnered from perception alone.
Realizing that humans can make mistakes in interpreting the information by relying solely on the five senses to perceive the world, Bacon argued that external variables must be taken into consideration. For instance, to determine if people get sick from being cold or wet, he insisted that they should be exposed to outside influences. By doing so, a theoretical pattern could be shown to determine if these influences resulted in more illness.