This is from Drawing on Art: Duchamp and Company by Dalia Judovitz, Marcel Duchamp.
Referring back to Guston’s remarks about Duchamp finding Rubens to be random and spontaneous (which I’m still calling the trance state).
Rudolph Arnheim… objected to Duchamp’s position, since he himself called for judgement and awareness on the part of the artist. For him, to talk about the artists as medium was to “attribute to him the kind of passivity and the kind of being an instrument” that ends up neglecting the very essence of the “artistic process.” Duchamp responded to Arnheim by clarifying that he did not mean “to make a medium of the artist but to compare him to the status of a medium,” given that “half of the creation is done by these onlookers.” Duchamp’s comparison of the artist to a medium does not diminish the artist’s capacity to make creative decisions. Rather, what Duchamp was challenging was the presumed coincidence between the artist’s understanding of his or her work and the work’s reception by the spectator or art institutions that would judge its merits:
I know that this statement will not meet with the approval of many artists who refuse the mediumistic role and insist on their awareness of the creative act–yet, art history has consistently decided upon the virtues of a work of art through considerations completely divorced from the rationalized explanations of the artist. (Writings of Marcel Duchamp).
Duchamp argued that while the artists may be full of the best intentions, he “plays no role at all in the judgement of his own work.” The artist’s decisions in the execution of the work are informed by intuitions, shaped by prior artistic gestures and conventions, that determine outcome. However, the fact that these intuitions cannot be fully known or accounted for by the artist in no way diminishes their impact and regulative force.
Here’s a link to the trance state of and Old Master
So here we have the supreme rationalist artist that the role of the artist is essentially mediumistic. As Guston noted, even the most rational artist is aware that the act of making art is in essence irrational.