This text, occasioned by a critical reading of Mathematics Education and Subjectivity (Brown, 2011) and constituting a response to the book, aims at contributing to the building of (post-structuralist) theory in mathematics education. Its purpose was to re/write two major positions that Mathematics Education and Subjectivity articulates: that which it takes with respect to (a) L. S. Vygotsky and the activity theory he gave rise to, which are subject and subjected to critique, and (b) Lacan and his theory of the subject, which radically change signification in and through their adoption in the book. Moving between languages becomes a major issue of theory building captured in the diction "traduttore, traditore" (translating is committing treason). The present text should be read as a contribution to an ongoing dialogue on theory, incomplete and partial, as (perfectly) imperfect as Mathematics Education and Subjectivity itself.