Terrence and I were in a combox the other day, and he asked me, whether Catholics would ever remember altars, and it took me aback, since every single Catholic church and very nearly every Catholic chapel, shrine, and space for common prayer has one, and they have become much more prominent and central since the most recent Ecumenical Council. He asked, "Document it. please?" But I'll need your help, my dear commentariat.
The importance and centrality of the altar of God I learned as a small child, back at that tiny rural parish the Church of the Guardian Angels, Copley Township OH. About thirty years ago, back in graduate school, I studied some about altars. But I don't remember my sources any more...... so feel free to supply some in the combox or in the email (there's links in the sidebar, and please use a clear subject line so it doesn't get lost in the mass spam deletions)
Altars began as flat-topped rock formations, or flat-topped piles of rocks left just the way God made them (using tools on them was illicit), large enough to lay out a slaughtered full-grown bull. The Lord's Temple had several altars of various sizes for various sacrifices --- holocausts, sin offerings, thanksgiving offerings, offerings of incense and of cereal grains, and so on, and the rules for them are set out in the book of Leviticus.
When the Church was formed, it also had its own thanksgiving offering, established by Christ at His last supper, and its own altars. The "breaking of the bread", the re-presentation of the Lord's one only sacrifice, was the core of Christian worship. The altar of sacrifice and the table of the Lord's thanksgiving feast are one and the same.
The first generations of Christians gathered on the Lord's Day, the first day of the week, in various places, including the living rooms of St. Lydia and the Chosen Lady to whom the Johannine epistles are written, and the burial places of St Polycarp and other martyred saints, where the grave marker was itself the altar. In the vision of the Apocalypse, we see the great square altar in heaven, beneath which the glorified martyred saints praise the Lord and the Lamb and offer up the prayers of the saints on earth. Still to this very day, we place relics of the saints underneath or inside every consecrated altar.
Eventually, Christianity became legal, and then favored by the governing powers, and the Church took over the pagan temples, exorcised them and consecrated them to the worship of the true only God. And it needed more space to accomodate all the new converts, so began building large public churches, taking over the basilica floor plan used for the emperor's assemblies, but where the pagans would have the emperor's throne or the emperor's idol, the Christians placed the altar of the Lord.
Now, here's where I'm not entirely clear when it started or how or why, but it did --- the altar began shrinking and moving further and further away, until it became just a shelf or ledge in the far wall with a symbolic piece of stone in it (the "altar stone"), oftentimes dwarfed into utter insignificance by a huge and beautiful reredos. Now, don't get me wrong, there is absolutely nothing wrong with a huge and beautiful reredos, especially one with many images of the glorified saints in heaven who worship with us --- except when it usurps the place and honor of the altar. It's just like gazing on the Lord in adoration, it is wonderful up until it supercedes and becomes more important than the actual reception of the Body and Blood of the Lord.
And then, starting early in the 20th century, predating the Council but I suspect about the same time as St Pius X's urging of frequent Communion and the beginnings of what was called the Liturgical Renewal Movement, altars began to become as architecturally central as they are central to our true worship. Solid, substantial, standing on their own, not a vestige or an afterthought.
So, my wise readers who get out to libraries or studied more recently than I did and still remember --- when did the shrinking of the altars start, and why?