A volume on the biliary system appeared in 1965, based on a symposium of the NATO Advanced Institute held in September, 1963, in Newcastle upon Tyne in England. It soon became an authorita­ tive text on the problems of the biliary tract and, for instance, the discussion on the biliary secretion of organic anions, organic cations and inorganic ions were classic references. The worn pages of the volume in many libraries, including my own, bespeak its usefulness over ten long years. The initiative and energy of the Director of the first Institute have to be admired, even more so since he was able to assemble a Second Institute in Aalborg, Denmark, in 1975. His wisdom is reflected in the selection of the subjects discussed. The comparison between the two volumes tells something about the advancement in the time interval in knowledge about liver and biliary tract diseases, about the turnover of researchers interested in the liver and its diseases, and also about the present philosophy in biologic science. For this com­ parison, this volume is particularly suited because, in contrast to many other recent conferences, the more leisurely pace of the NATO Institutes permits more comprehensive but still scholarly reviews of the problems. The foreword of the first volume, written by my colleague, the late Harry Sobotka, expresses his, now dated, astonishment about the progress of knowledge of biology of the bile, so much less accessible to study than urine.