"In 1943, the US psychologist Abraham Maslow published a paper called A Theory of Human Motivation, in which he said that people had five sets of needs, which come in a particular order. As each level of needs is satisfied, the desire to fulfil the next set kicks in. First, we have the basic needs for bodily functioning - fulfilled by eating, drinking and going to the toilet. Maslow also included sexual needs in this group. Then there is the desire to be safe, and secure in the knowledge that those basic needs will be fulfilled in the future too. After that comes our need for love, friendship and company. At this stage, Maslow writes, the individual "may even forget that once, when he was hungry, he sneered at love". The next stage is all about social recognition, status and respect. And the final stage, represented in the graphic as the topmost tip of the triangle, Maslow labelled with the psychologists' term "self-actualisation". It's about fulfilment - doing the thing that you were put on the planet to do. "A musician must make music, an artist must paint, a poet must write, if he is to be ultimately happy," wrote Maslow. "What a man can be, he must be." While there were no pyramids or triangles in the original paper, Maslow's hierarchy of needs is now usually illustrated with the symbol. And although the paper was written as pure psychology it has found its main application in management theory."