Pachomius,
I wouldn’t make the distinction between the terms “eternal” and “eternity”. Both terms could refer to either reality. In this case, the very same word is being used in two different ways.
Human beings (at least souls) are by nature eternal in the sense of infinite succession, and hence even though the Church is a supernatural society, you could argue that it has a kind of natural eternity. However, I would also argue that there is a certain sense in which the Church (and those enjoying the beatific vision which will one day be the entire Church) can participates in God’s eternity and hence participates in some sense in being outside of time. As I mentioned, clearly this participation is limited, but I would never want to deny it altogether. We also need to keep in mind that there is a sense in which God actually came into time in the Incarnation. In taking on flesh, God took upon Himself a temporal existence. This doesn’t mean that He “left” eternity would would be a contradiction, but He assumed a second nature. This fact of God entering time (and not simply actings in it) has profound implications for the nature of the Church, which as you pointed out, is the Mystical Body of Christ and intimately united with Him.
Katholish has done a great job in delineating how
eternality is held by the Church. His discourse brings to mind the two different “infinities” extant. On the one hand, there is what is termed “actual” infinity. It’s only representation is God. It has no beginning, no middle and no end. It is outside of time. It engulfs all of time and beyond. It engulfs all of matter and all of motion, and, like time, is beyond all matter and motion. It is in this sense that God is “eternal.”
On the other hand, there is what is termed “potential” infinity. This is that which has some or many of the properties of an actual infinity, but has not reached actuality yet. In other words, it is still proceeding towards infinity. As long as it continues in the direction of actualizing, it continues to
be. It will never stop; it just continues and continues, and unlike the pink bunny, it will continue to continue. Its nature is to forever and ever be in potential to be an actual infinity, but we call it by the same word, “infinity”. It is in this sense that we are eternal.
If at any point a potential infinity should stop, it will only be, at that point, finite. It has part of the characteristics of the infinity that belongs only to God as long as it continues in motion, to expand, to add matter, to add souls, and to add time. However, infinity cannot be acquired; if it is not possessed for all eternity it can never be possessed. As the Church teaches (in
The Teachings of the Catholic Church, Ch. III,
The One God, By the Rev. A. L. Reys, Vol. I, pg. 89, printed 1962) “That which is infinite in any respect is necessarily infinite in all respects, for infinite cannot be limited to this or that quality, but by definition includes all in all. It follows that whatever is finite in any respect is by that fact alone known to be finite in every respect.”
So, as was said by others, the duration of a being is its continued existence. But, when duration consists of a series of different states succeeding each other, this is what we call temporal. Thus, these successive states can be measured by clocks and our universal concepts of time. Duration which is not a composition of successive states but is one continuous state with no beginning or end is called eternal. The ability to be able to compare stages or states with each other is successive duration and is subject to time and, thus, not eternal.
jd