Where did Freud's iceberg metaphor of mind come from?

Look at any introductory psychology book that covers psychoanalysis, and you are likely to find an image of an iceberg floating in the sea. The image serves as an illustrative metaphor for Freud's theory of the mind: Only a fragment of our ideas and feelings are conscious or "visible" to us, while the vast bulk of our mental content is unconscious or "invisible" to everyday introspection. A simple Internet search of the terms "Freud iceberg" will bring forth hundreds of examples. The problem is that Freud never mentioned the iceberg in his published writings. It is a metaphor that has become ubiquitous in (English-language) writings about Freudian theory, but that does not find its source in his work. So the question is, where did it come from? Much attention has been directed to a passage in Ernest Jones's biography of Freud. Many have taken this to mean that the Freudian iceberg metaphor derives directly from Fechner. Jones encouraged this interpretation, quoting Freud on being "open to the ideas of G. T. Fechner and following that thinker upon many important points." The iceberg metaphor of mind has another source with a solid connection to Freud: Granville Stanley Hall. Hall was one of the founders of American psychology. The mystery of the Freudian iceberg is not completely resolved, but we have made considerable progress. The mystery that remains is why Hall believed the metaphor's origin to lay somewhere in Fechner's writings. (PsycINFO Database Record (c) 2019 APA, all rights reserved).