Let our powers combine
Cicero was a homo novus, a New Man, a middle-class provincial elbowing his way into Rome's exclusive senatorial class. At the start of his career, he lacked the dignitas, the personal dignity and social clout, necessary to give his words unquestioned authority. Writing was Cicero’s way of legitimizing his speaking; and Tiro, in a sense, became his master's voice. (Di Renzo, "His Master's Voice" 9)
It's interesting that such a captivating speaker depended so heavily on writing to bolster his work--he enjoyed the best of both worlds, thanks to Tiro's talent. I can't help but wonder how Socrates would have responded to such evidence of writing's legitimacy as a useful tool for the public speaker.