 The lack of abstraction ability in these studies was statistically significantly higher in the VA patients and it has thus been construed as indicating pathology.As persons with mental illness are generally believed to demonstrate "concrete" thinking (a tendency to interpret abstract concepts literally) the research results have, in practice, often been improperly generalized to suggest proverbs alone can be a sufficient indicator of mental illness.A "concrete" interpretation of the proverb "a rolling stone gathers no moss" would simply restate the proverb in different words, rather than delivering any metaphorical meaning.