Another etymology proposed by Nigidius Figulus is related by Macrobius: "Ianus" would be Apollo and Diana "Iana", by the addition of a "D" for the sake of euphony. This explanation has been accepted by A. B. Cook and J. G. Frazer. It supports all the assimilations of Janus to the bright sky, the sun and the moon. It supposes a former *Dianus, formed on *dia- < *dy-eð2 from the Indo-European root *dey- shine represented in Latin by "dies" day, Diovis and Iuppiter. However the form Dianus postulated by Nigidius is not attested.