This essay is mainly a restatement of the biohistorical ideology such as we developed it during recent years. At a recent international congress, I tried to present this in a detached, logical way (1965). At other times, I endeavoured to clarify it by using a case history (1964). In both cases, certain things remained unexplained and I will now try to elucidate the development of our biohistorical ideology along somewhat different lines. In doing so I shall avoid unnecessary personal reminiscences, but some facts of a personal nature or relating to the development of our Institute necessarily will have to be recapitulated in this connection. Many factors are involved, ranging from the increase in our staff, to the augmenting interests of our students (which forces us to pay some special attention to their education and, just as any editor will learn much through his editorial activities, one learns so much more by teaching than I formerly understood or expected). Other factors again are the increase of our library holdings and documentation programme, talks with colleagues (particularly in the literary faculty) and those visitors from abroad who do not come only — welcome as they are — to copy certain data from various sections of our Index Ultrajectinus (a world index of the literature of biohistory, entirely separate from our Library Catalogue). Then, one makes schemes which frequently do not materialize rightaway, but which nevertheless are most helpful in planning for the future. As to our ideology, there is very little new in it, if considered from the point of view of the great medical humanists of the past. The materia medica, however, is only partially identical with the materia biologica and it took me many years to apply the ideology of the medical humanists to our own subject matter. Most medical historians always considered it a very natural thing to enter a variety of humanistic pastures and, whenever their rambles went beyond the traditional fields of history s.s., they never felt an urge to employ another term for whatever they were doing than “history of medicine”.