Herbert Spencer has established in his "Principles of Sociology" that the mausoleum was the egg out of which the temple was evolved. The first cave-dwellers buried their dead in the grottoes in which they had lived, and themselves moved into others. They periodically revisited the sepulchres to bring offerings to the dead. In time the deceased ancestor became invested by the imagination of his descendants with supernatural powers, and ascended from stage to stage till he was exalted into a deity. Thenceforth his cave became a temple. Ferguson, writing of the Chaldæan temples, and indicating their resemblance to tombs says, "The most celebrated example of this form is as often called (by ancient writers) the tomb or the temple of Belus, and among a Turanian people the tomb and the temple may be considered as one and the same thing." [Footnote: Clement of Alexandria (Exhort. to the Heathen) had already said, "Temples were originally Tombs." _Cf_. also Eusebius (Præp. Evangelica ii. 6) heads the chapter, "The Temples of the Gods that are none other than Tombs."] In the primitive Church there were, as we have seen, churches which had no connection whatever with sepulchres, and chapels underground that contained tombs. The current of popular feeling set so strongly towards the latter that the Popes yielded to it, as did also the Bishops, and converted every basilica into a mausoleum by the transfer to it of the bones of a saint. But that was not all. The Holy Mysteries had been celebrated in private houses and basilicas on wooden tables, sometimes square, but often round, and with three legs. An illustration is in the cemetery of S. Calixtus, of the latter half of the second century, where a priest is represented celebrating at what looks like a modern tea-table. According to William of Malmesbury, S. Wulstan, Bishop of Worcester (1062-1095), destroyed the wooden altars in his diocese, which had been universal in England, _altarea lignea jam inde a priscis diebus in Anglia_. But with the transformation of the basilica into a mausoleum, the altar was also transformed into a sepulchre. If it did not contain the entire body of a saint, it had a hole cut in it to receive a box containing relics; and the Roman pontifical and liturgy were altered in accordance with this. The Bishop on consecrating an altar was to exact that it should contain relics, and the priest on approaching it was required to invoke the saints whose bones were stored in it. [Footnote: Pontifex accepta mitra, intigit policem dextræ manus in sanctum Chrisma et cum eo signat confessionem, id est sepulchrum altaris, in quo reliquiæ deponendæ. _Pont. Roman._ The priest on ascending to the altar kisses it, and refers to the relics contained in it. "Oramus te, Domine, per merita sanctorum tuorum quorum reliquiæ hic sunt--ut indulgere digneris omnia peccata mea."] The cavity in the slab to contain the relics was liturgically entitled _sepulchrum_.