“The ones that weren't paintable were the ones I did paint. The dead. To start with, I wanted more to paint the whole business, the world as it then was, the living reality – I was thinking in terms of something big and comprehensive. But then it all evolved quite differently, in the direction of death. And that's really not all that unpaintable. Far from it, in fact. Death and suffering have always been an artistic theme. Basically, it's the theme. We've eventually managed to wean ourselves away from it, with our nice, tidy lifestyle... They [ Red Army Faction-members were not the victims of any specific ideology of the left or of the right, but of the ideological posture as such. This has to do with the everlasting human dilemma in general: to work for a revolution and fail..”

In an interview (March 1960) with David Sylvester, edited for broadcasting by the BBC first published in ‘Living Arts, June 1963; as quoted in Interviews with American Artists, by David Sylvester; Chatto & Windus, London 2001, p. 31
1960s

Source: 1945 - 1964, Interview, 1960, p. 107

Source: Quotes, 1960 - 1970, Questions to Stella and Judd' - September 1966, p. 117

In a letter to her parents, from Worpswede, 10 September 1899; as quoted in Voicing our visions, – Writings by women artists; ed. Mara R. Witzling, Universe New York, 1991, p. 199
1899

Quoted in Pierre Daix, La Vie de Peintre de Pablo Picasso, Paris: Editions du Seuil, 1977.
Picasso explained his friend Pierre Daix (around 1965), why he started painting in blue early around 1905. Picasso had made a portrait of Carles Casagemas in 1899.
1970s
Original: C’est en passant que Casagemas était mort que je me suis mis à piendre en bleu

Letter written in 1943; cited from Jeremy Hooker and Gweno Lewis (eds.) Selected Poems of Alun Lewis (London: Unwin, 1987) p. 108.

Source: Quotes, 1960 - 1970, Questions to Stella and Judd' - September 1966, p. 120

lightly edited
Other sources