In school we learn classical mathematics, the mathematics known before the year 1900. It has a direct relation to the actual world. Arithmetic is related to counting and measurement, algebra to general truths about calculations, geometry and trigonometry to the sizes and shapes of objects, calculus to the velocities of moving objects and a host of other applications. Students have no difficulty in knowing what it is about and what it is for. Students who go on to modern mathematics, the mathematics of the present century, either in university or by private study, find it considerably different. There is no immediate contact with reality, and they may find it hard to visualise what is being discussed.