St. John Chrystostome, Church Father and Doctor of the Church (4th Century): Panegyric on St. Lucianus, "Do not be surprised that I should equate martyrdom with baptism; for here too the spirit blows with much fruitfulness, and a marvellous and astonishing remission of sins and cleansing of the soul is effected; and just as those who are baptized by water, so, too, those who suffer martyrdom are cleansed with their own blood."
Homilies on the Acts of the Apostles, Homily I: "But why does Christ say, "Ye shall be baptized," when in fact there was no water in the upper room? Because the more essential part of Baptism is the Spirit, through Whom indeed the water has its operation; in the same manner our Lord also is said to be anointed, not that He had ever been anointed with oil, but because He had received the Spirit. Besides, we do in fact find them receiving a baptism with water [and a baptism with the Spirit], and these at different moments. In our case both take place under one act, but then they were divided."