Pope Zosimus established that a large candle be blessed on the Holy Sabbath of the Pasch, which the deacon blesses after benediction has been received from the priest. This candle designates Christ: in the wax humanity, in the fire divinity; and as it illuminates it precedes the catechumens to baptism, just as once a column of fire preceded the children of Israel as they crossed the Red Sea, illuminating by fire and shading by a cloud. (Hugh of St. Victor, De Sacramentis, 2.9.5, Deferrari's translation)
There's my next Easter Vigil homily, should the Holy Spirit ever give me the opportunity again! One could go a lot of places with this particular image of the divinity and humanity of Christ, but I'll tell you right now, not all of them would be orthodox. I'll be careful, I promise. I'll be sure to have my homily certified. Get it?