This liber amicorum honours Professor Jan Tissot van Patot as a scholar, referring in particular to his concern with transport economics. The signi­ ficance of his work grew out of his influence within Netherlands Railways as, with the passage of the years, he dedicated himself increasingly to the vastly wider field of transport economics. I would emphasize, however, that his theoretical knowledge and views in wider contexts have also been of great value to Netherlands Railways, and I greatly appreciate this opport­ unity of referring to this aspect in a few personal words. It is characteristic both of his person and his attitude that his work was often the occasion for contacts of a more personal nature, contacts which were profoundly marked by his philosophy and convictions. Our relations date from more than thirty-seven years ago, when he asked me for a con­ tribution for a magazine which he helped to edit at that time and which was concerned with the same field as I was. We became colleagues when he entered the service of NS, the Netherlands Railways. His sphere of work at that time was such that he was consulted more and more frequently by others. His particular value to NS has been the increased dimension of transport policy and decision making he added to the company's existing policy and decision making.