IX. OF THE CREATION OF THE ANGELS
Yes, for each of them is a pure spirit which can come into being only by way of creation (LXI. 1).
When were all the angels created by God?
The angels were created by God instantaneously at the same time when He created all the contents of the corporal world (LXI. 3). Were the angels created by God in a locality?
Yes, the harmony of the divine work demanding this (LXI. 4, Obj. i).
What is the locality where the angels were created called?
We call it heaven simply, and sometimes the empyrean heaven (LXI. 4).
What does the empyrean heaven mean?
It means a place full of glory and splendour which is the most beautiful part of the corporal world (ibid.).
Is the empyrean heaven the same as the heaven of the blessed?
Yes (ibid. Obj. 3).
(Next - X. OF THE PROBATION OF THE ANGELS)
Pegues OP, R P Thomas. Catechism of the "Summa Theologica" of Saint Thomas Aquinas for the Use of the Faithful (pp. 52-54). Veritatis Splendor Publications. Kindle Edition.