St. Ambrose (Doctor of The Church. Bishop of Milan from 374 A.D. to 397 A.D. Venerated as Saint by Catholics and Orthodox)
Our Savior has appointed two kinds of resurrection in the Apocalypse. 'Blessed is he that hath part in the first resurrection,' for such come to grace without judgment. As for those who do not come to the first, but are reserved unto the second resurrection, these shall be disciplined until their appointed times, between the first and the second resurrection; or, if they should not have fulfilled them then, they shall remain still longer in punishment until they have paid the very last farthing.
--Psalmum I Enarratio (Exposition on Plalm 1), section 36.