I recently wrote an article about the thoughts of Ven. Fulton J. Sheen on the subject of Purgatory.
Here is a paragraph from his book The Moral Universe: A Preface to Christian Living.
Three possible states await a soul after death:
a state of perfect Love without suffering which is heaven;
a state of suffering without Love which is hell,
and a state of Love with suffering which is Purgatory.
Purgatory is a creation of the mercy of God. (128)
A PDF of the article can be found here.