And I saw as it were a sea of glass mingled with fire: and them that had gotten the victory over the beast, and over his image, and over his mark, and over the number of his name, stand on the sea of glass, having the harps of God.
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Bede
AD 735
glass: That is, the pellucid fount of Baptism, which is consecrated by the fire of the Holy Ghost. Or else: because it pertains to the nature of fire, in that it is made red by martyrdom.