The tourist trade is booming. With all this coming and going , you'd expect greater understanding to develope between the nations of the world. Not a bit of it! Superb systems of communication by air , sea and land make it possible for us to visit each other's countries at a moderate cost. What was once the 'grand tour' ,reserved for only the very rich , is now within everybody's grasp. The package tour and chartered fights are not to be sneered at. Modern travellers enjoy a level of comfort which the lords and ladies on grand tours in the old days couldn't have dreamed of. But what's the sense of this mass exchange of populations if the nations of the world remain basically ignorant of each other?