As Christianity met with Paganism over the centuries, it picked up some of the local paganic ideas. J.B. Russell summarizes the situation in this period: "The Christian concept of the Devil was influenced by folklore elements, some from the older, Mediterranean cultures and others from the Celtic, Teutonic and Slavic religions of the north. Pagan ideas penetrated Christianity while Christian ideas penetrated paganism" (1). Thus the Celtic god of the underworld, Cernunnos, "the horned god", was easily assimilated into Christianity, just as the pagan feast of December 25th was adopted as 'Christmas'. The horned gods of the Scandinavians were easily compared to the Devil- and hence the idea that the Devil has horns became more popular in Christian art [although there is absolutely no Biblical association of the Devil with horns]. Hilda Davidson carefully researched Scandinavian views of the Devil figure and showed at great length how these ideas were accommodated into Christianity- rather that the radical call of the Gospel and the Kingdom of God being presented as it is, a fundamentally different worldview (2). Once the Devil was associated with Pan, he became presented as having hooves, goat hair and a large nose (3). No longer was Satan pictured with long dark hair, but rather spikey hair like the Northern European gods of evil. Thus 'converts' to Christianity were allowed to keep some of their existing ideas, and these soon became part of the core fabric of popular 'Christianity'. For example, the northern European fear of demons entering a person led them to cover their mouths when they yawned, and to fear sneezing as the intake of air could allow demons to rush in to the person. Christianity adopted these practices, adding the phrase "God bless you" whenever someone sneezed, in an attempt to Christianize the practice.