From the Iliad

"He...handed him murderous symbols, which he inscribed in a folding tablet, enough to destroy life, and told him to show it to his wife's father, that he might perish." -- p. 157, book 6

So, this king dude wants to kill this other guy for no real reason... but rather than do it himself, he writes a letter to his father in law and hands it to the guy he wants dead. The guy then delivers it to the father in law, who reads it and sends the guy on various quests, doing various heroic deeds, in hopes that he'll die. (He doesn't.)

But the insinuation, in Homer, is that the writing itself will kill the guy. (Who, if you're curious, is Bellerophontes.) The writing is so powerful that it could kill Bellerophontes simply because he cannot read. How ironic! This man carries his own death sentence to someone who will carry it out, and he does so because, due to his inability to read, he doesn't know it's a death sentence.

:awesome: