Based on his clinical work with patients experiencing severe aphasia, the author asks questions of both a scientific and existential nature. That language plays a role in thinking seems to be a commonly accepted proposition, but the nature and extent of that role are difficult to define. It is also generally suggested that people are distinguished from animals through their use of language, and that to be human is ‘to be a linguistic being’. This article explores the implications of these propositions for patients with severe language impairments and with very limited communication possibilities. How, and to what extent, do disturbed language processes play a role in the consciousness, feelings of identity and ‘being human’ of these patients? Some answers to these questions are sought in the linguistics of de Saussure, Freud’s theories of language considered in light of recent cognitive neuroscientific insights, and Lacan’s ideas concerning language and the subject.