There is great interest in brain function as a result of the new laboratory and imaging techniques in the neurosciences. Psychoanalysis has embraced these contributions without adequate assessment of whether they bridge the mind/brain divide and provide answers to the questions psychoanalysts ask. A review and critique of the biological theories of dreaming highlights their limitations and points out they do not address the semantics, meaning, and content of dreaming nor the pragmatics of dreaming, its function. At best these theories attempt to provide the syntax of dreaming, the form dreaming takes. Brain biology cannot provide the transduction rules to go from neuronal firing to the psychological experience of dreaming or other mind states.