Throughout history man has navigated himself or his vehicle; while some of the methods he has used have remained unchanged through the centuries, other methods have been developed, and when superseded by later developments often lost. The stone age cave dweller used navigation, after chasing his quarry, to find his way back to his cave and this particular form of the art of navigation is little changed today. On the other hand the arts and the techniques which enabled early Polynesian navigators to sail the South Seas, and the crews of Arabian dhows to return to their home ports unerringly, may well be lost for all time. We do not propose to regret this; it is part of the evolutionary process that as each skill is lost it is replaced by a greater skill. The modern marine sextant can trace its ancestry back to the practice of measuring the height of a star in finger breadths used by those Arab navigators. Aerial navigation entirely, and from our limited knowledge we suggest ship navigation also, is at a point in its development where the man is being replaced by the machine, and it may be that we should assess the best way to ensure that we, as navigators, remain master of that machine.