Sextus Empiricus reports arguments against voice and mental movements as truth bearers. I argue that some of these arguments are Stoic and justify the Stoic view that truth and falsity belong to a third item, the lekton – the incorporeal signification of linguistic utterances. The argument against voice is that only significant voice can be true or false, but those who do not speak our language can hear our voice without understanding the signification. So truth cannot lie in the voice, but in its signification, by grasping which we recognise the truth or falsity of what someone has said. Mental movements are private to each individual and others cannot even know for sure what another person’s thoughts are, let alone whether they are true or false. There would be no way to establish an agreement on what is true. These arguments contain the desiderata that a truth bearer must be publicly accessible and able to be known. These desiderata are fulfilled by lekta as they are signified by linguistic utterances but not identical to mental movements. In this way, I propose to answer the question of why the Stoic truth bearers are lekta and not something else.