“Blessed be the hour in which I was first led to inquire into my own spiritual nature and destination! All my doubts are removed; I know what I can know, and have no fears for what I cannot know. I am satisfied; perfect clearness and harmony reign in my soul, and a new and more glorious existence begins for me. My entire destiny I cannot comprehend; what I am to become, exceeds my present power of conception. A part, which is concealed from me, is visible to the father of spirits. I know only that it is secure, everlasting and glorious. That part of it which is confided to me I know, for it is the root of all my other knowledge.”

Jane Sinnett, trans 1846 p. 13
The Vocation of Man (1800), Doubt

Wenn ich nur dasjenige weiß, und von ihm überzeugt bin, was ich selbst gefunden, – nur dasjenige wirklich kenne, was ich selbst erfahren habe, so kann ich in der That nicht sagen, daß ich über meine Bestimmung das Geringste wisse; ich weiß blos, was Andre darüber zu wissen behaupten.
Source: The Vocation of Man (1800), P. Preuss, trans. (1987), p. 4

Quote of Friedrich, 1821; as cited in Authenticity and Fiction in the Russian Literary Journey, 1790-1840 (2000) by Andreas Schönle, p. 108, from memoirs of Vasily Zhukovsky
Variant translation: I have to stay alone in order to fully contemplate and feel nature.
This answer of Friedrich is recorded by Vasily Zhukovsky who asked the painter in 1821 to travel together to Switzerland
1794 - 1840

Rome, 5 December
Without Dogma (1891)

Apocalypse (1930)
Context: What man most passionately wants is his living wholeness and his living unison, not his own isolate salvation of his "soul." Man wants his physical fulfillment first and foremost, since now, once and once only, he is in the flesh and potent. For man, the vast marvel is to be alive. For man, as for flower and beast and bird, the supreme triumph is to be most vividly, most perfectly alive. Whatever the unborn and the dead may know, they cannot know the beauty, the marvel of being alive in the flesh. The dead may look after the afterwards. But the magnificent here and now of life in the flesh is ours, and ours alone, and ours only for a time. We ought to dance with rapture that we should be alive and in the flesh, and part of the living, incarnate cosmos. I am part of the sun as my eye is part of me. That I am part of the earth my feet know perfectly, and my blood is part of the sea. My soul knows that I am part of the human race, my soul is an organic part of the great human soul, as my spirit is part of my nation. In my own very self, I am part of my family. There is nothing of me that is alone and absolute except my mind, and we shall find that the mind has no existence by itself, it is only the glitter of the sun on the surface of the waters.

Fully Booked: Q & A with John Banville (2012)