“I am all at once what Christ is, ' since he was what I am, and
This Jack, joke, poor potsherd, ' patch, matchwood, immortal diamond,
Is immortal diamond.”

From Lu Tong (also spelled as Lu Tung)
Misattributed

Source: Laughter in the Dark

Earth Abides

My Reviewers Reviewed (lecture from June 27, 1877, San Francisco, CA)

This is from an anecdote found in St. Nicholas magazine, Vol. 5, No. 4, (February 1878) http://www.gutenberg.org/files/15331/15331-h/15331-h.htm :
Sir Isaac Newton had on his table a pile of papers upon which were written calculations that had taken him twenty years to make. One evening, he left the room for a few minutes, and when he came back he found that his little dog "Diamond" had overturned a candle and set fire to the precious papers, of which nothing was left but a heap of ashes.

Dryad Song (1900)
Context: I am immortal! I know it! I feel it!
Hope floods my heart with delight!
Running on air mad with life dizzy, reeling,
Upward I mount, — faith is sight, life is feeling,
Hope is the day-star of might!

"The Immortal" (1949)

Autobiography of Values (1978)
Context: I grow aware of various forms of man and of myself. I am form and I am formless, I am life and I am matter, mortal and immortal. I am one and many — myself and humanity in flux. I extend a multiple of ways in experience in space. I am myself now, lying on my back in the jungle grass, passing through the ether between satellites and stars. My aging body transmits an ageless life stream. Molecular and atomic replacement change life's composition. Molecules take part in structure and in training, countless trillions of them. After my death, the molecules of my being will return to the earth and sky. They came from the stars. I am of the stars.

Source: Dictionary of Burning Words of Brilliant Writers (1895), P. 592.