“I have come to believe that this is a mighty continent which was hitherto unknown. I am greatly supported in this view by reason of this great river, and by this sea which is fresh.”

"A New Refutation of Time" (1946) [" Nueva refutación del tiempo http://www.monografias.com/trabajos11/filoylit/filoylit.shtml"]
Variant translations:
And yet, and yet... Denying temporal succession, denying the self, denying the astronomical universe, are obvious acts of desperation and secret consolation. Our fate (unlike the hell of Swedenborg or the hell of Tibetan mythology) is not frightful because it is unreal; it is frightful because it is irreversible and ironclad. Time is the thing I am made of. Time is a river that sweeps me along, but I am the river; it is a tiger that tears me apart, but I am the tiger; it is a fire that consumes me, but I am the fire. The world, unfortunately, is real; I, unfortunately, am Borges.
Time is the substance from which I am made. Time is a river which carries me along, but I am the river; it is a tiger that devours me, but I am the tiger; it is a fire that consumes me, but I am the fire.
Other Inquisitions (1952)
Source: Labyrinths: Selected Stories and Other Writings
Context: Time is the substance I am made of. Time is a river which sweeps me along, but I am the river; it is a tiger which destroys me, but I am the tiger; it is a fire which consumes me, but I am the fire. The world, unfortunately, is real; I, unfortunately, am Borges.
Context: And yet, and yet... Denying temporal succession, denying the self, denying the astronomical universe, are apparent desperations and secret consolations. Our destiny is not frightful by being unreal; it is frightful because it is irreversible and iron-clad. Time is the substance I am made of. Time is a river which sweeps me along, but I am the river; it is a tiger which destroys me, but I am the tiger; it is a fire which consumes me, but I am the fire. The world, unfortunately, is real; I, unfortunately, am Borges.

1880s, Inaugural address (1881)

Address to the Constituent Assembly (1947)

"Seven American Nights", Orbit 20 (1978), ed. Damon Knight, Reprinted in Gene Wolfe, The Island of Doctor Death and Other Stories and Other Stories (1980), Reprinted in Gene Wolfe, The Best of Gene Wolfe (2009)
Fiction

Knowing Yourself: The True in the False (1996)

From a letter to Robert W. Gordon (February 4, 1925)
Letters

Steadfast and gentle father, in your kindness respond to me, your unworthy servant, who has never, from her earliest childhood, lived one hour free from anxiety. In your piety and wisdom look in your spirit, as you have been taught by the Holy Spirit, and from your heart bring comfort to your handmaiden.
Letter to Bernard, Abbot of Clairvaux, 1146-47

Arthur's commentary
The Nemesis of Faith (1849)
Context: It is strange, when something rises before us as a possibility which we have hitherto believed to be very dreadful, we fancy it is a great crisis; that when we pass it we shall be different beings; some mighty change will have swept over our nature, and we shall lose entirely all our old selves, and become others. … Yet, when the thing, whether good or evil, is done, we find we were mistaken; we are seemingly much the same — neither much better nor worse; and then we cannot make it out; on either side there is a weakening of faith; we fancy we have been taken in; the mountain has heen in lahour, and we are perplexed to find the good less powerful than we expected, and the evil less evil.

The Tale of Taleisin