John the Baptist haloes, as sufficiently recognisable without them, but a saint in the background, not usually present in this scene, has a ring halo to denote his status. In the High Renaissance, even most Italian painters dispensed with haloes altogether, but in the Church's reaction to the Protestant Reformation, that culminated in the decrees on images of the Council of Trent of 1563, their use was mandated by clerical writers on religious art such as Molanus and Saint Carlo Borromeo. Figures were placed where natural light sources would highlight their heads, or instead more discreet quasi-naturalistic flickering or glowing light was shown around the head of Christ and other figures (perhaps pioneered by Titian in his late period). Rembrandt's etchings, for example, show a variety of solutions of all of these types, as well as a majority with no halo effect at all. The disk halo was rarely used for figures from classical mythology in the Renaissance, although they are sometimes seen, especially in the classical radiant form, in Mannerist and Baroque art. By the 19th century haloes had become unusual in Western mainstream art, although retained in iconic and popular images, and sometimes as a medievalising effect. When John Millais gives his otherwise realist St Stephen (1895) a ring halo, it seems rather surprising. In popular graphic culture, a simple ring has become the predominant representation of a halo since at least the late 19th century, as seen for example in the logo for the Simon Templar ("The Saint") series of novels and other adaptations. Spiritual significance in Christianity The early Church Fathers expended much rhetorical energy on conceptions of God as a source of light; among other things this was because "in the controversies in the 4th century over the consubstantiality of the Father and the Son, the relation of the ray to the source was the most cogent example of emanation and of distinct forms with a common substance" – key concepts in the theological thought of the time. A more Catholic interpretation is that the halo represents the light of divine grace suffusing the soul, which is perfectly united and in harmony with the physical body. In the theology of the Eastern Orthodox Church, an icon is a "window into heaven" through which Christ and the Saints in heaven can be seen and communicated with. The gold ground of the icon indicates that what is