Description of an early Christian baptismal rite of converts from paganism:

Ideally...one's baptism would come on Easter eve, during the midnight vigil. At the appointed hour, the baptizand (the person to be baptized) would depart the church for the baptistery, which typically housed a large baptismal pool or (if possible) flowing stream. There, in the semidarkness of that place, he or she would disrobe and--amid a host of blessings, exhortations, unctions, and prayers--descend naked into the waters, to be immersed three times by the bishop, in the name of the Father, then of the Son, and finally of the Holy Spirit. The newly baptized Christian would then emerge from the waters to be anointed with the oil of chrismation, the seal of the Holy Spirit, and to don a new garment of white, and would return to the church to see the Eucharist celebrated--and to partake of it--for the first time. On that night, the erstwhile catechumen would have died to his or her old way of life and received a new and better life in Christ.
--Hart (below)