[W. Bion's contribution to the discussion on nature vs. nurture. Early development and psychosis].

This papers presents a Mother-baby model of interaction that generates the capacity to think, linked to emotional life. With this model is possible to shorten the distances between those who think that mental pathology is caused by constitutional factors and those who use the "tabula rasa" model and assume that the environment failures are the cause of the pathology. The relation between concreteness and abstraction is explored as the basis for the capacity to mental development.