This paper was presented to a Conference on the theme 'The Formulation of Interpretations in Clinical Practice'. It suggests that, impressionistically in line with the identification of psychoanalysis with natural science, an unconscious metaphor which sees interpretation as something like a force inserted on a physical particle has been more influential conceptually than the unconscious metaphor naturally complementary to it, that of interpretation as something like a liquid in flow.

The concept of 'the collateral interpretation' is introduced. Loosely speaking, this is what an analyst thinks he would interpret at any given moment. It is tentative, unformed, and changes kaleidoscopically. It accommodates psychoanalytic concepts. It is suggested that examination of the mode of operation of 'the collateral interpretation' is important in understanding the formulation of interpretations.