"I understand now the spiritual mark of these momentary states. I understand it through my monochromes; and the mark of the momentary states of the flesh, through in the imprints pulled from the bodies of my models. … But the mark of the momentary states of nature? … I leap outside and there I am on the riverbank amidst the bulrush and the reeds. I dust everything with pigments and the wind, which bends the delicate stems, comes to apply it with precision and delicacy upon my canvas that I thus present to the trembling nature: I obtain a vegetal mark. Then it begins to rain, a fine spring shower; I expose my canvas to the rain, and it is done. I have captured the mark of rain! The mark of an atmospheric occurrence …
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It become completely natural that the model at last leaves the studio with me and that I take imprints of nature, and that the model should be there suddenly, taking her place in nature, and also mark the canvas there, where she feels good, in the grass, amidst the reeds, at the waterside or beneath a waterfall, naked, in a static pose or in motion, as a true and, ultimately, completely integrated subject of nature. All phenomena of nature as subject, human, animal, vegetal, mineral, or atmospheric are of interest to me for my naturometrics."
Yves Klein Le monochrome 1960, Truth becomes reality
"A few months ago, for example, I felt the urge to register the signs of atmospheric behavior by recording on a canvas the instantaneous traces of spring showers, of south winds, and of lightning (Needless to say,catastrophe). For instance, a trip from Paris to Nice might have been a waste of time had I not spent it profitably by recording the wind. I placed a canvas, freshly coated with paint, upon the roof of my white Citroen. As I zoomed down Route Nationale 7 at the speed of 100 kilometers an hour, the heat, the cold, the light, the wind, and the rain all combined to age my canvas prematurely. At least thirty to forty years were condensed into one day. The only annoying thing about this project is that I have to travel with my painting all the time.
My atmospheric imprints of a few months ago had been preluded a year ago by vegetal imprints. After all, my purpose is to extract and conclude the trace of the immediate from any incidence of natural objects – human, animal, vegetable, or atmospheric circumstances."
Yves Klein, Chelsea Hotel Manifesto, 1961