Eating on Erev Yom Kippur

"Anybody that eats on the ninth shall be considered as one who has fasted on the ninth and tenth" (paraphrase) This simply means that if you prepare yourself before Yom Kippur, with the ninth referring metephorically to the days leading up to Yom Kippur and eating reffering metephorically to the preparation, it will be considered as if you had an extended Yom Kippur