"The paschal vigil is not the fulfillment of the triduum in the sense of a 'final' celebration: it is a commencement. . . .
"—The liturgy of the paschal fire: relatively late in its current form ([of a] fire kindled [out] in front of the church), it was in [its] origins a rite of the lucernarium, [an] ancient gesture inherited from that moment in domestic life when one lit the lamps in the house before nightfall. In keeping with the Jewish manner of reckoning the day from evening to evening, this rite of the candlestick marked the entry into the new day. Hence the importance of this entry in the paschal celebration: Lent began with ashes, this liturgy of the fire opens the heart of the assembly to the newness of the Resurrection. The communication of fire to each of the faithful, the procession, and the acclamation of the Exsultet come and stamp their seal on this irruption of the paschal newness into the heart of the night."
Daniel Bourgeois "«Les images liturgiques sont des images folles»: essai sur la structure du triduum paschal," Communio: revue catholique internationale 35, nos. 1-2 (janvier-avril 2010): 117 (103-118).