Simeon Solomon was one of Britain's most interesting and challenging painters: Jewish, openly gay, witty and sensitive, but also reckless, self-indulgent and self-destructive. His finest pictures were glowing and sensitive 'synaesthetic' renderings of poetry and music in paint. This watercolour, from his best period, in pristine condition and one of his most important and attractive works, was exhibited at the Dudley Gallery in 1869. The Dudley in the 1860s, before the Grosvenor Gallery opened in 1877, was the London exhibition venue where progressive painters showed their work, dubbed (insultingly) by a critic the 'poetry-without-grammar' school, sister to the so-called (also insultingly) 'fleshly school of poetry'.

Solomon's pictures were greatly admired by the critics in the 1860s, but by 1872 The Guardian could write that Solomon had 'taken to draw sickly dreams which can give no healthy pleasure'. Even before Solomon's arrest in 1873 for public indecency, which led to his final disgrace, his reputation was suffering. The year 1868, the date of our picture, was a breaking point for him; his best customer, Frederick Leyland, rejected his Sacramentum Amoris, a single-figure watercolour which Swinburne described as having 'a super sexual beauty in which the lineaments of man and woman seem blended' (Leyland had paid for it in advance but it is now lost, along with eight other Solomons belonging to Leyland).

The moment depicted in A Song is in the hush immediately after the last note of music has died away. The audience, and the player herself, are visibly moved by what they have just heard. Many features in A Song are unexplained: the subject of the tapestry, whether the blossom is apple, walnut, myrtle or cherry, the meaning of the crystal ball, the meaning of the dropped sash, and the meaning of the wings motif at the breast of the leftmost figure who looks a little like Swinburne, but none of this is important because A Song is about music. Solomon referred to the picture as A Song of Spring whilst he was painting it (in a letter to Leyland in 1868), and it was originally exhibited in 1869 as A Song, but it was not exhibited under its third title of A Prelude by Bach until the Royal Academy Winter Exhibition in 1906, a year after Solomon's death. Solomon's original title A Song of Spring suggests that the music which has died away in the picture might have been Mendelssohn's 'Spring Song'.

The costume is vaguely in the Regency style, the boys dressed in silk breeches and blouses, and the girls in a mixture of empire-waisted and classical dresses, all in the colours of finely wrapped Belgian pastries, chiming across the composition. The figures are choreographed in frieze-like groups, and posed in classical attitudes. Solomon had been in Florence and Rome in 1866 and in 1867, and both the colour and design of A Song are reminiscent of the 1st century BC Roman Aldobrandini Wedding fresco in the Vatican, which he would have known. Christopher Payne has suggested that the Italianesque ebony and ivory harpsichord or piano is English, made by Jackson and Graham in the mid-1860s to a design by George Aitchison, the architect of Leighton House, perhaps made for Leyland. The shallow space and the design of the tapestry against the panelling in the background may derive from paintings by Albert Moore of the mid-1860s, The Shulamite of 1864-66 in particular (a painting which is also about the frozen pause at the end of a song).