This quote is a follow on from this previous post. I came across it while reading Heinz Kohut and Ernest Wolf on Self Psychology. Like the earlier Freud quote, it has relevance to the modern debate on psychiatric diagnosis:
"The best efforts of the past [...] are no exception to the rule that the simplified correlation of specific patterns of manifest behaviour with universally present psychological conditions which of necessity forms part of any such typology will, in the long run, impede scientific progress. Why then, do we persist in the attempt to devise characterologies? The answer is that such classifications, even though we must be aware of the fact that they may eventually limit our thinking and stand in our way, can for a while be valuable guides in psychological territory in which we feel not yet at home."Kohut, H., Wolf, E.S. (1978). The Disorders of the Self and their Treatment: An Outline. Int. J. Psycho-Anal., 59:413-425.