The testimony of scientists and others indicates that the processes of problem solving are not entirely open to consciousness. One may begin by reasoning consciously and deliberately, but the solution often comes in its own time, suddenly and ‘out of nowhere.’ Internal search implies searching people’s memories while external search implies looking further afield and consulting papers, books, journals, and even consultants. In the case of internal search there is a tendency to search at a local level or in the area of the problem in the first instance since this will produce solutions quickly if any are to be found. Common sense would seem to dictate that a systematic approach is by far the best one to take. One really has to approach a problem with an eye on its context, since the same problem may require a different approach in another situation.