This article shows how the first series of Diderot’s ‘Salons’ (1759 to 1765) implement the intermedial project of the ‘philosophe’ – namely to depict paintings presented in Paris salons to foreign readers of Grimm’s ‘Correspondance littéraire’ – and how they, at the same time, contain the seeds of his final abandonment of art criticism. In 1761, Diderot established the famous comparison between literary style and colour in painting; with this formula, he thought himself to be able to solve the challenges of his task for Grimm’s periodical. However, in the ‘Salon de 1763’, he realised that even his meticulously detailed descriptions could not match the paintings; the result of this conclusion was outlined in his reflections on battle pieces. These considerations, which he re-published in 1765 and then in 1767, finally lead him to leave Grimm’s ‘Correspondance littéraire’ and art criticism in 1769. In 1765 however, Diderot was far from being disheartened. The first Diderot’s ‘Salons’ outlines a true poetic of approximation.