The importance of Giel's work should be found primarily in his contribution to the scientific underpinning of psychiatry. However, the research instruments now available in psychiatry, some of them developed at Giel's own department, don't only yield profit. Fleck, a Polish bacteriologist and philosopher of science, has demonstrated that scientific observation and interpretation are strongly influenced by collective and culture-bound concepts. For example, in classification systems like DSM-III-R, the only relevance of basic psychopathological phenomena is their potential usefulness for the recognition of disorders. However, their scientific significance shouldn't be confined to this. The advantage of the now available research instruments will be lost, if one doesn't realise continuously their principal limitations and one-sidedness.