“Wings I saw springing
from fair women's shoulders,
and from beneath rubble
I've seen butterflies flutter.”

Paris Review interview (1996)

As translated by Lin Yutang
Alternative translations
Once upon a time, I, Chuang Chou, dreamt I was a butterfly, fluttering hither and thither, a veritable butterfly, enjoying itself to the full of its bent, and not knowing it was Chuang Chou. Suddenly I awoke, and came to myself, the veritable Chuang Chou. Now I do not know whether it was then I dreamt I was a butterfly, or whether I am now a butterfly dreaming I am a man. Between me and the butterfly there must be a difference. This is an instance of transformation.
As translated by James Legge, and quoted in The Three Religions of China: Lectures Delivered at Oxford (1913) by William Edward Soothill, p. 75
Once Zhuang Zhou dreamed he was a butterfly, a fluttering butterfly. What fun he had, doing as he pleased! He did not know he was Zhou. Suddenly he woke up and found himself to be Zhou. He did not know whether Zhou had dreamed he was a butterfly or a butterfly had dreamed he was Zhou. Between Zhou and the butterfly there must be some distinction. This is what is meant by the transformation of things.
One night, Zhuangzi dreamed of being a butterfly — a happy butterfly, showing off and doing things as he pleased, unaware of being Zhuangzi. Suddenly he awoke, drowsily, Zhuangzi again. And he could not tell whether it was Zhuangzi who had dreamt the butterfly or the butterfly dreaming Zhuangzi. But there must be some difference between them! This is called 'the transformation of things'.
Once upon a time, Chuang Chou dreamed that he was a butterfly, a butterfly flitting about happily enjoying himself. He didn’t know that he was Chou. Suddenly he awoke and was palpably Chou. He didn’t know whether he were Chou who had dreamed of being a butterfly, or a butterfly who was dreaming that he was Chou.
Context: Once upon a time, I, Chuang Chou, dreamt I was a butterfly, fluttering hither and thither, to all intents and purposes a butterfly. I was conscious only of my happiness as a butterfly, unaware that I was Chou. Soon I awaked, and there I was, veritably myself again. Now I do not know whether I was then a man dreaming I was a butterfly, or whether I am now a butterfly, dreaming I am a man. Between a man and a butterfly there is necessarily a distinction. The transition is called the transformation of material things.

The Rubaiyat (1120)

Source: Cosmos (1980), p. 20 http://books.google.com/books?id=pxK-jkLVHK0C&q=Sagan+%22butterflies+who+flutter+for+a+day%22&dq=Sagan+%22butterflies+who+flutter+for+a+day%22&ei=3sGoSbb2JIHCzgS05LjsAw&pgis=1

Closing words of graveside oration at the funeral of Jeremiah O'Donovan Rossa, 1 August 1915. The Cause Of Ireland, Liz Curtis, Beyond the Pale Publications, Belfast 1994, pg 266
Context: Our foes are strong and wise and wary; but, strong and wise and wary as they are, they cannot undo the miracles of God Who ripens in the hearts of young men the seeds sown by the young men of a former generation. And the seeds sown by the young men of '65 and '67 are coming to their miraculous ripening today. Rulers and Defenders of the Realm had need to be wary if they would guard against such processes. Life springs from death; and from the graves of patriot men and women spring living nations. The Defenders of this Realm have worked well in secret and in the open. They think that they have pacified Ireland. They think that they have purchased half of us and intimidated the other half. They think that they have foreseen everything, think that they have provided against everything; but, the fools, the fools, the fools! — They have left us our Fenian dead, and while Ireland holds these graves, Ireland unfree shall never be at peace.

Stanza 1.
I Wandered Lonely as a Cloud http://www.bartleby.com/145/ww260.html (1804)
Source: I Wander'd Lonely as a Cloud

Source: Last Sacrifice

Che de le spine ancor nascon le rose,
E d'una fetida erba nasce il giglio.
Canto XXVII, stanza 121 (tr. W. S. Rose)
Orlando Furioso (1532)