http://agathe.gr/democracy/the_speakers.html
The Speakers Litigants spoke on their own behalf, although occasionally using speeches prepared by trained professionals; skillful rhetoric was necessary in order to sway a jury. The speeches written by ... They say, too, that as he progressed in his ability to speak he had a mirror made as large as himself and kept his eyes on it while practicing, that he might correct his faults; and that he used to go down to the shore at Phaleron and address his remarks to the roar of the waves, that he might not be disconcerted if the people should ever make a disturbance; and that because he was short of breath he paid Neoptolemos the actor ten thousand drachmas to teach him to speak whole paragraphs without taking breath.