4.  After these things, ye were led to the holy pool κολυμβήθραν.  The pool or piscina was deep enough for total immersion, and large enough for many to be baptized at once.  Cf. Bingh. Ant. VIII. vii. 2; XI. xi. 2, 3.  For engravings of the very ancient Baptisteries at Aquileia and Ravenna, shewing the form of the font or piscina, see Dict. Christian Ant. “Baptistery.” of Divine Baptism, as Christ was carried from the Cross to the Sepulchre which is before our eyes.  And each of you was asked, whether he believed in the name of the Father, and of the Son, and of the Holy Ghost, and ye made that saving confession, and descended three times into the water, and ascended again; here also hinting by a symbol at the three days burial of Christ The same significance is attributed to the trine immersion by many Fathers, but a different explanation is given by Tertullian (Adv. Praxean, c. xxvi.):  “Not once only, but three times, we are immersed into the several Persons at the mention of their several names.”  Gregory of Nyssa (On the Baptism of Christ, p. 520 in this Series) joins both reasons together:  “By doing this thrice we represent for ourselves that grace of the Resurrection which was wrought in three days:  and this we do, not receiving the Sacrament in silence, but while there are spoken over us the Names of the Three Sacred Persons on whom we believed, &c.”  Compare p. 529.  Cf. Apost. Const VIII. § 47, Can. 50:  “If any Bishop or Presbyter does not perform the three immersions of one initiation, but one immersion made into the death of Christ, let him be deprived.” Milles in his note on this passage mentions that “this form of Baptism is still used in the Greek Church.  See Eucholog. p. 355.  Ed. Jac. Goar. and his notes p. 365.”.  For as our Saviour passed three days and three nights in the heart of the earth, so you also in your first ascent out of the water, represented the first day of Christ in the earth, and by your descent, the night; for as he who is in the night, no longer sees, but he who is in the day, remains in the light, so in the descent, as in the night, ye saw nothing, but in ascending again ye were as in the day.  And at the self-same moment ye were both dying and being born; and that Water of salvation was at once your grave and your mother.  And what Solomon spoke of others will suit you also; for he said, in that case, There is a time to bear and a time to die Eccles. iii. 2.; but to you, in the reverse order, there was a time to die and a time to be born; and one and the same time effected both of these, and your birth went hand in hand with your death.