“What does your conscience say? — "You shall become the person you are."”
                                        
                                        Was sagt dein Gewissen? 
'Du sollst der werden, der du bist.' 
Variant translation: Become who you are. 
It is noted  here http://www.anonymityone.com/Faq97.htm,  here http://www.google.it/search?num=100&hl=en&safe=off&q=%22Become%20who%20you%20are%22+Pindar+Nietzsche&um=1&ie=UTF-8&tbo=u&tbm=bks and  here http://www.google.it/search?num=100&hl=it&safe=off&biw=1440&bih=690&q=%22%28become+what+you+are%29+after+the+ancient+Greek+poet+Pindar.+See+Ecce+Homo+%28Nietzsche%29%22 that the phrase was first used by Pindar, and was merely re-used by Nietzsche. 
Sec. 270 
The Gay Science (1882)