Greek theology and its canonical iconography have not been studied nearly as much as the Byzantine, although the religious character of pagan art is no less pronounced. When it is studied it is mostly in the representations on the vases. Sculpture, however, in particular terra-cotta and ivory figurines and plaques, and votive offerings in sanctuaries, offers a wide scope for such a study. Greek piety created some standard forms of votive offerings such as the crouching child, the protome, male or female, the seated or standing woman, sometimes exactly identifiable from the attributes.
A standard type of votive offering, perhaps not as common as the single figure, is that of reliefs, statuettes and statues representing two, or sometimes more, female figures, identical or slightly differentiated, traditionally explained as Demeter and Kore or the Nymphs.
The topic has been treated variously since the early nineteenth century, in isolated examples, or regional and other groups. There is no treatment of it in its entirety in the Greek world, and not much progress has been made in the subject since the basic nineteenth-century treatises. Moreover, in the above publications, never cited in more recent works, one finds some very sound approaches and knowledge of the textual evidence. However, in these early publications the material is mostly Classical, or Hellenistic and Roman. In some of the cases of double figures discussed in them, the duplication, rather than ‘doubleness’, is more apparent than real because the attributes are repeated and are those of the unique war goddess Athena, or the equally unique Tyche or Fortuna. However, the case is not always so, especially in archaic or earlier times, and it gets even more complicated when the figures are not two but three and sometimes more, even up to nine. The repeating of figures, often under one mantle, as diad, triad, etc., could be explained as multiplication of a figure by the folk-mind (mythology), followed by the Greek artists, thus creating the Eileithyiai, Horai, Charites, Muses, etc. Modern scholars have insisted on trying to identify in all of them Demeter and Kore, the female diad par excellence.