The essential feature of the piaculum is that it is an expiation for wrong-doing, and the victim is often human.
By way of expiation for their crime the Danaides were condemned to the endless task of filling with water a vessel which had no bottom.
Thus McLeod Campbell (q.v.) held that Christ atoned by offering up to God a perfect confession of the sins of mankind and an adequate repentance for them, with which divine justice is satisfied, and a full expiation is made for human guilt.
This conception of the pilgrimage, as a means of expiation or a source of pardon for wrong, was foreign to the ancient Church.