The combination of tangible reality with a visionary and spiritual atmosphere was one of the features that explain the fascination exerted by Murillo’s works, many of them extremely popular, which is why the Catholic Church used his images for the following three centuries. A fair number of his themes are not specifically described in the Bible and some, such as the scenes from the childhood of Christ and Saint John the Baptist, were his own inventions. As in this painting, Murillo portrayed complex theological concepts in easily understandable and sincere images that appealed immediately to the human emotions. The exquisite colours of this painting, with its very rich tonalities, and the manner in which the paint is applied illustrate how Murillo was a forerunner of 18th-century techniques. For this reason his style was enormously attractive to cultivated travellers such as Joseph Townsend, who states in his account of his stay in Spain that "no other Spaniard has equalled him in expression and sweetness". This is one of various works on Christ´s childhood and it has been one of Murillo´s best known paintings and one of the most popular with the Spanish public since it was first exhibited (1819) at the Museo del Prado. The anecdotic atmosphere of this religious image, in the style of genre painting, is reflected in the name by which it is known, The Children with the Shell, which was coined by Federico de Madrazo, director of the Prado, in the 1872 catalogue. Although these holy children display an idealised beauty that is absent from the children depicted in Murillo´s genre paintings, their gestures and expressions are very lifelike. The painting has always been admired for its special charm and for Murillo´s masterful achievement of fluidity and subtlety in the figures, which are bathed in a limpid, silvery light. Although it is not known who the first owner was, the painting was most likely painted for a private client rather than a religious institution, as Murillo´s religious images adapted well to the luxurious interiors of the devout and wealthy Sevillian faithful. Indeed, the painter created an art that was appropriate to household environments. Murillo´s religious works were collected by two of his main patrons, Justino de Neve and Nicolas Omazur, and their popularity among private owners is beyond all doubt following Kinkead´s research. Mayer noted a relationship between this composition and a print made after a painting by Guido Reni (Bartsch, no. 13), possibly inspired by Annibale Carracci. The Children with the Shell is a reflection of a popular form of piety that favoured representing Christ and Saint John the Baptist as children, placing emphasis on both their spirituality and human condition. In this case the theme contradicts the strict ecclesiastical doctrine since, as Francisco Pacheco pointed out in El arte de la pintura (1649), Christ and Saint John the Baptist, although cousins, did not meet until they were both adults, when the latter baptised Jesus in the river Jordan. The most outstanding feature of this anecdote is that it foreshadows in childhood an event that occurred in Christ´s adult life: his baptism by Saint John in the river Jordan. The Christ Child smiles and points towards the soft light emanating from the golden mist formed by the clouds into which the angels appear to merge. In the background dark, threatening storm clouds seem to predict the destiny of both Children. On Saint John´s cross, a ribbon in the manner of a scroll flutters with the inscription "ecce agnus dei", proclaiming the Christ Child as "lamb of God". By placing the lamb in the foreground staring at the two boys, Murillo emphasises its duality as symbol of Christ and favourite companion of any child, thereby placing the religious event in a domestic context. There are several fairly interesting known copies of this composition in Cologne, Richmond and Vienna, among other places.

De Tiziano a Goya: grandes maestros del Museo del Prado, Madrid, Museo Nacional del Prado: SEACEX, 2007, p.231