Once Nietzsche said that human beings may be divided into two categories: Apollonians and Dionysians*. By this the philosopher meant that there are human beings a) who know what they are going to do in the long-term future (what we now call the grant application for the next 5 years), i. e. , Apollonians, and b) who barely know what they are going to do tomorrow morning before breakfast, i. e. , Dionysians. ** To organize a symposium, this symposium in particular, a committee had to be formed either of individuals sharing both Nietzschean characteristics or of individuals possessing either characteristic. Considering the rarity of the former type of subject, this organizing committee was spontaneously formed by a typical sample of both types of individuals. We first met in Perugia in 1988. Those of us who were Apollonians had thus a chance to organize a programme. The Dionysians knew what was going to happen to them, but, of course, did not know yet how to cope with it. They duly did so every day of the meeting, after breakfast. The organizers decided that it would be a useful exercise to assemble experts having different perspectives but all pursuing a very rapidly developing aspect of cell biology. They also hoped that these selected Apollonians and Dionysians would not merely recount their results but try to project the future through active interchanges of ideas and opinions with other attendees.

Interest in and emphasis upon different aspects of the sphingolipids have, in general, followed the biochemical developments of the day. The early inves- tigators were preoccupied principally with the isolation of "pure" compounds and structural elucidation. This historical perspective is found in the discus- sion presented in Chapter 1 (Section 1. 1. 2 and Table III). Still, the isolation and structural characterization of glycolipids are the basic foundation of all our knowledge of enzymology, immunology, and cell biology. Recent infor- mation obtained on structure has greatly affected the interpretation of various phenomena related to glycolipids. New structures suggest a new role of gly- colipids as antigens and receptors. Ten years ago, only four neutral glycolipids and two gangliosides were known in human erythrocytes. We now know structures of at least twenty additional neutral glycolipids and ten additional gangliosides in human erythrocytes that are known to be important blood group, heterophil, and autoantigens. Erythrocytes are only one example of a cell type whose glycolipid profile has been extensively studied. Our defective knowledge in immunology and cell biology may be due to incomplete un- derstanding of structural chemistry. Modern methodology based on methyla- tion analysis, mass spectrometry, and enzymatic degradation has supple- mented classical analysis based on clorimetry. Nuclear magnetic resonance spectroscopy is still in the development stage, but will eventually replace var- ious chemical analyses. However, important future studies should be directed toward elucidating the organizational structure of glycolipids in membranes.