The endless wealth of information on the internet sharpens the question: how much and what is really important for us to remember? This issue is related to questions regarding the core processes involved in reasoning and thinking. We present mental manipulation (MM) as the core of reasoning and examine the above-mentioned issue in light of MM's vital role in reasoning and problem-solving. WHAT IS MENTAL MANIPULATION? Richard Feynman, Nobel Laureate in Physics (in 1965), tells the following story (Feynman & Leighton, 1997). When he was a kid, he was known for fixing radios. One day a guy asked him to fix a radio that made tremendous noise when it was turned on. Feynman turned on the radio, heard the noise, and started thinking as he walked back and forth. "I realize that one way it can happen is that the tubes are heating up in the wrong order-that is, the amplifier's all hot, the tubes are ready to go, and there's nothing feeding in, or there's some back circuit feeding in, or … and therefore it's making a lot of noise … " The guy said, "You come to fix the radio, but you're only walking back and forth!" Feynman responded "I'm thinking!" and continued to describe his thinking to himself: " … take the tubes out, and reverse the order completely in the set." So, he changed the tubes around, stepped to the front of the radio, turned the thing on, and it is as quiet as a lamb: it [the radio] waits until it heats up, and then plays perfectly-no noise. The guy got Feynman other jobs, and kept telling everybody what a tremendous genius he was, saying, "He fixes radios by thinking!" "The whole idea of thinking, to fix a radio … he never thought that was possible." (pp. 19-20). Feynman actually describes a classical exemplar of mental manipulation (MM); he