“When the doctrine of allegiance to party can utterly up-end a man's moral constitution and make a temporary fool of him besides, what excuse are you going to offer for preaching it, teaching it, extending it, perpetuating it? Shall you say, the best good of the country demands allegiance to party? Shall you also say it demands that a man kick his truth and his conscience into the gutter, and become a mouthing lunatic, besides?”

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)

Source: Just Folks (1917), The Man To Be, lines from stanza 3.

Dover 2005, p. 236
The Ego and Its Own (1845)

in Quotable Patri http://patrifriedman.com/quotes/patri.html

Such is the rule of honor.
Opening to 'Omerta', from the album Ashes Of The Wake
Lyrics

Speech to the Virginia Convention (1861)
Context: These are pregnant statements; they avow a sentiment, a political principle of action, a sentiment of hatred to slavery as extreme as hatred can exist. The political principle here avowed is, that his action against slavery is not to be restrained by the Constitution of the United States, as interpreted by the Supreme Court of the United States. I say, if you can find any degree of hatred greater than that, I should like to see it. This is the sentiment of the chosen leader of the Black Republican party; and can you doubt that it is not entertained by every solitary member of that same party? You cannot, I think. He is a representative man; his sentiments are the sentiments of his party; his principles of political action are the principles of political action of his party. I say, then; it is true, at least, that the Republican party of the North hates slavery.

XVIII, 3
The Kitáb-I-Asmá

The Fantastic Imagination (1893)
Source: A Dish of Orts
Context: A fairytale, a sonata, a gathering storm, a limitless night, seizes you and sweeps you away: do you begin at once to wrestle with it and ask whence its power over you, whither it is carrying you? The law of each is in the mind of its composer; that law makes one man feel this way, another man feel that way. To one the sonata is a world of odour and beauty, to another of soothing only and sweetness. To one, the cloudy rendezvous is a wild dance, with a terror at its heart; to another, a majestic march of heavenly hosts, with Truth in their centre pointing their course, but as yet restraining her voice. The greatest forces lie in the region of the uncomprehended.
I will go farther. The best thing you can do for your fellow, next to rousing his conscience, is — not to give him things to think about, but to wake things up that are in him; or say, to make him think things for himself. The best Nature does for us is to work in us such moods in which thoughts of high import arise. Does any aspect of Nature wake but one thought? Does she ever suggest only one definite thing? Does she make any two men in the same place at the same moment think the same thing? Is she therefore a failure, because she is not definite? Is it nothing that she rouses the something deeper than the understanding — the power that underlies thoughts? Does she not set feeling, and so thinking at work? Would it be better that she did this after one fashion and not after many fashions? Nature is mood-engendering, thought-provoking: such ought the sonata, such ought the fairytale to be.