“About 1883 a kind of break occurred in my work. I had wrung Impressionism dry, and had come to the conclusion that I knew neither how to paint nor how to draw. In a word, I was at an impasse”

Source: CAT'S EYE.

Foreword http://www.psychedelic-library.org/childf.htm
LSD : My Problem Child (1980)
Context: There are experiences that most of us are hesitant to speak about, because they do not conform to everyday reality and defy rational explanation. These are not particular external occurrences, but rather events of our inner lives, which are generally dismissed as figments of the imagination and barred from our memory. Suddenly, the familiar view of our surroundings is transformed in a strange, delightful, or alarming way: it appears to us in a new light, takes on a special meaning. Such an experience can be as light and fleeting as a breath of air, or it can imprint itself deeply upon our minds.
One enchantment of that kind, which I experienced in childhood, has remained remarkably vivid in my memory ever since. It happened on a May morning — I have forgotten the year — but I can still point to the exact spot where it occurred, on a forest path on Martinsberg above Baden, Switzerland. As I strolled through the freshly greened woods filled with bird song and lit up by the morning sun, all at once everything appeared in an uncommonly clear light. Was this something I had simply failed to notice before? Was I suddenly discovering the spring forest as it actually looked? It shone with the most beautiful radiance, speaking to the heart, as though it wanted to encompass me in its majesty. I was filled with an indescribable sensation of joy, oneness, and blissful security.
I have no idea how long I stood there spellbound. But I recall the anxious concern I felt as the radiance slowly dissolved and I hiked on: how could a vision that was so real and convincing, so directly and deeply felt — how could it end so soon? And how could I tell anyone about it, as my overflowing joy compelled me to do, since I knew there were no words to describe what I had seen? It seemed strange that I, as a child, had seen something so marvelous, something that adults obviously did not perceive — for I had never heard them mention it.
While still a child, I experienced several more of these deeply euphoric moments on my rambles through forest and meadow. It was these experiences that shaped the main outlines of my world view and convinced me of the existence of a miraculous, powerful, unfathomable reality that was hidden from everyday sight.

Found attributed to Michelangelo in non-specialist publications as early as 1929 https://books.google.com/books?id=-0YhAQAAMAAJ&dq=If+people+knew+how+hard+I+had+to+work+to+gain+my+mastery%2C+it+would+not+seem+so+wonderful+at+all.&focus=searchwithinvolume&q=michelangelo, but no source is known. Not found in any known biography of Michelangelo.
Disputed

Associated Press (2008); from an interview conducted by John Rogers.

Source: Henry Rios series of novels, Rag and Bone (2001), p.174

Bella Swan, p. 219
Twilight series, New Moon (2006)

Vol. 1: 'My beautiful One, My Unique!', pp. 130-140
1895 - 1905, Lettres à un Inconnu, 1901 – 1905; Museo Communale, Ascona

Anna Wulf, in "Free Women: 4"
The Golden Notebook (1962)

Source: Ayandegan (1973), p. 4