The Pharmakon refers to a contradiction inherent within writing, within the act of writing. It refers to the difficulties associated with recording the spoken work, not practically or physically, but in relation to how it affects each form of communication, the spoken word as well as the written. How writing actually affects the verifiability, the truth, of that which had been spoken.
Socrates’ fable concerning the invention of writing. It is recounted by Plato in his collection of writings under the title Phaedrus (presumably composed in around 370bc), recording dialogues between Socrates and Phaedrus.