Chapter 13: On the eternity of God; definition
CHAPTER THIRTEEN. On the eternity of God.
There follows GOD's sixth attribute, namely eternity, which is His highest perfection, by which He is free from finite duration. The word eternity properly notes a standing duration without beginning, middle, end, without flux of past, present, future.
Among the ancients Boethius defines thus: Eternity is the whole, simultaneous, and perfect possession of interminable life — or it is interminable, indivisible, and independent duration.
Latin
CAPUT DECIMUMTERTIUM, De aeternitate Dei. Sequitur sextum DEI attributum, aeternitas videlicet, quae est summa illius perfectio, qua expers est finitae durationis. Aeternitatis vox notat proprie durationem stativam sine principio, medio, fine, sine fluxu praeteriti, praesentis, futuri. Ex antiquis Boethius ita definit: Aeternitas est interminabilis vitae tota simul et perfecta possessio, vel est duratio interminabilis, indivisibilis et independens.