It would not, therefore, be fitting that such souls should be given
into their power to be tormented by them. Again, when the devils tempt
wayfarers, they do it because they hope to lead them into sin, however
perfect they may be; but they could have no such hope about the souls
in Purgatory, and so would not be likely to tempt them. Besides, they
know that their temptations or harassings would have an effect not
intended by them, and would bring the souls from Purgatory to Heaven
more quickly.

* * * * *

It is the common law that souls in Purgatory, during the whole time
that they are there, cannot come out from the prison, even if they
wish; The constant closing of the prison-doors is a part of the
severity of their punishment. So teach St. John Chrysostom, St.
Athanasius, and St. Augustine.... The reason for this is the law of the
justice of God. The souls of the lost are kept in prison by force and
against their will. The souls in Purgatory stay there willingly, for
they understand the just will of God and submit to it. This law,
however, can be sometimes dispensed with; and so St. Augustine holds it
to be probable that there are often true apparitions of the Holy Souls
by the permission of God.... It is true that, as a rule, these are
apparitions of souls, who, by a special decree of God, are suffering
their Purgatory somewhere in this world.... One thing, however, we must
note in these cases. When such a permission is given, the pain of the
soul is not interrupted. This is not only seen from the visions
themselves, but is what reason requires.

* * * * *