Knowledge is very fundamental in the life of a person and it is therefore very necessary to fully understand the various ways of knowing. Traditionally, there are four basic ways of knowing which were developed by different philosophers. These four ways of knowing are depicted in the TOK diagram of knowledge. The sources of knowledge represented in the TOK diagram include sense perception, language, emotion and logic. Sense perception is the first way of knowing that is based on body senses such as vision and touch (Lehrer 34). The second source of knowledge is language and in this case knowledge is passed down from those in authority and through reading. Language is used as a medium to pass knowledge from one person to another. The third source of knowledge according to the TOK diagram is emotion. Knowledge about certain things is obtained through intuition and emotional feeling. The fourth and final source of knowledge according to the TOK diagram is logic which emphasizes the importance of reasoning as a source of knowledge. Rational thinking leads to generation of ideas and solutions that become a very important source of knowledge and understanding. Philosophers and psychologists claim that there is a fifth way of knowing that is yet to be fully exploited. Many scholars agree that memory plays a very significant role in helping a person know and understand things (Lehrer 112). Although memory as a way of knowing is not featured on the TOK diagram, many scholars agree that it plays a significant role in generating crucial information that is used in historical studies and social science. This paper will substatatiate and explain why memory is an important source of knowledge apart from the four ways of knowing highlighted in the TOK diagram. The idea of classifying memory as a source of knowledge is always discussed in most TOK discussions. Memory is a concept that combines different sources of knowledge and is normally used by many people to make knowledge claims. Memory is a combination of past experiences, perception and emotion. Ideas generated by memory are reliable but not in all instances (Dicker 59). Some of the ideas generated by memory end up being faulty and hence not trustworthy at times. Cases of mistaken identity are very common in courts and it is therefore true to say that the reliability of memory as a source of information or knowledge is not a hundred percent. There are instances where eyewitnesses commit a lot of errors in their testimonies due to forgetfulness and misconception. The fact that eyewitnesses can not be completely relied upon in a court of law makes many people to question whether memory is a reliable way of knowing. It is believed that memory can easily be altered if a person uses drugs or listens to other suggestions. The memory of a person keeps changing as time passes with the one that is relived more that once losing its truthfulness over time (Dicker 78). The mind of a human being is very vulnerable and it can therefore be easily manipulated by other external sources. The fact that the memory of a person can easily be influenced under different circumstances proves that it is sometimes difficult to find the actual truth of a particular case by completely relying on memory.