Rational intelligence is dangerous and leads to ratiocination. The painter is a medium who doesn't realize what he is doing. No translation can express the mystery of sensibility, a word, still unreliable, which is nevertheless the basis of painting or poetry, like a kind of alchemy.

In this quote, Marcel Duchamp critiques the role of rational intelligence in art, suggesting that it can be limiting and even dangerous when applied too rigidly. He argues that the over-reliance on ratiocination, or logical reasoning, in art creation can hinder true expression. Duchamp believes that the painter (and by extension, the artist) operates more as a medium, channeling emotions and ideas in ways they may not fully understand or control, which makes the process more instinctive and unconscious.

Duchamp also touches on the elusive nature of sensibility in art, describing it as a mysterious and somewhat unreliable force that still forms the foundation of creative expression. He contends that no translation, be it verbal or conceptual, can truly capture this intangible quality of art. Instead, sensibility works like alchemy, a kind of mystical transformation that transcends logical explanation, forming the core of both painting and poetry. It is this inexplicable quality that gives art its power and depth.

The origin of the quote reflects Duchamp’s broader philosophy about art. As one of the pioneers of the Dada movement and an influential figure in modern art, Duchamp constantly challenged traditional artistic norms. He was particularly interested in the tension between reason and intuition in creative practice. His works often defied conventional boundaries and rejected rational explanations, aiming instead to provoke and engage viewers on an emotional and subconscious level.

In essence, Duchamp's quote suggests that true artistic creation comes not from logic or reasoning, but from the unconscious and mysterious processes that defy verbal expression. This view encourages artists to trust their instincts and sensibility, rather than relying solely on rational thought, and to embrace the alchemy of art that transforms raw emotions into powerful, ineffable works.