"One who doesn't build the Beit HaMikdash in their own time, it's as though they had destroyed it." (Talmud Yerushalmi, Yoma 1:1.)
Even those who are pillars of the world go to their rest without building the Beit HaMikdash in their days. But in truth, the righteous in every era do build in their days a part of the Beit HaMikdash! Each one adds the spark which comes from his/her own heart.
The idea that "anyone who doesn't build the Beit HaMikdash in their days, it's as though they had destroyed it" -- that means someone who doesn't understand which aspect of Torah learning is truly their own. That's the part of the Beit HaMikdash that person is supposed to be building, and if one doesn't know, then one doesn't build.
So one must pray for redemption, and to strengthen one's knowledge, and one's awe, and to understand what one doesn't yet know. That's what it means to "go up to the place which God has chosen." (Deut. 17:8.)
That's the Hasidic master known as the Bnei Yissachar (R. Zvi Elimelech Spira of Dinov, who died in 1841.) He's commenting on a line from the Jerusalem Talmud which says that one who doesn't rebuild the Beit HaMikdash -- the Temple in Jerusalem -- in his own time is as guilty of its destruction as those who tore the Temple down.
That's a tough idea for those of us who have ambivalent feelings about the whole notion of the Temple. Most liberal Jews today decidedly do not wish to restore Temple sacrifice. (Neither Reform nor Reconstructionist Judaism nurtures this hope.) We tend to see the the destruction of the Temple as the brokenness out of which the new paradigm of rabbinic Judaism could emerge, and we don't want to return to the old paradigm. There's also the matter of contemporary geopolitics; two Muslim holy sites now occupy the top of that mountain.
The Bnei Yissaschar, though, offers a reading which I find really beautiful. The righteous in every era do rebuild the house of holiness, he says; each of us lifts up the spark in our own soul and our own heart, and together we collaborate on healing the cosmic rupture. Someone who doesn't rebuild, and who is therefore considered (by the sages) to be as guilty as the actual destroyers -- that means someone who doesn't take the time to learn which aspect of Torah is truly their own, which spark they're meant to uplift.
I love the idea that each of us can contribute a spark to the building of the Beit HaMikdash. The Bnei Yissachar is not talking about actually rebuilding a structure out of stones and mortar. Rather, he's talking about co-creating a spiritual structure of transformation through putting our hearts and souls together. And I love the idea that we do this, each of us, by learning the Torah which is truly ours to learn and to teach, and then lifting up the sparks of that learning and teaching to God.
How do I know which Torah is mine? Which Torah I most need to learn and to teach in order to contribute my irreplaceable spark to this collective enterprise? I don't have an easy answer to that. Sometimes I think that "my" Torah is the Torah which most powerfully calls to me and which makes me yearn to share it with others. Other times I think that "my" Torah is whatever Torah I most need to wrestle with: the tough texts, the painful passages, what I need to redeem in my own ways. Often I suspect I won't know which Torah was most truly mine until my life nears its end -- if then.
During these Three Weeks when Jews around the world are mourning the long-ago siege of Jerusalem and the fall of the Temple, the shattering of the place where we once felt we had a "direct line" to God, at least I can continue to learn Torah. And maybe I'll happen upon the teaching I most need to learn, and most need to teach, in order to do my part in the rebuilding which has nothing to do with the physical world of real estate and everything to do with the heights of holiness in the human heart.
With thanks to R' Eliot Ginsburg.