Glory to Jesus Christ!
I am inclined to agree with Cleopa, it is best to study the Philokalia with spiritual direction. However most people who read it probably don’t. I have the first four volumes and I have barely touched it, preferring to concentrate on other things. It is basically from the tradition of the Greek fathers but I believe it extends into the era of Gregory Palamas and that would be beyond the commonly accepted time of the Great Schism.
Better yet, there
is a great compendium of the Philokalia available from Light and Life Publishing company called, of all things
Philokalia - The Bible of Orthodox Spirituality, imagine that! It’s very good, I recommend it highly.
With Asteroid I warmly suggest
The Art of Prayer - an Orthodox Anthology compiled by Igumen Chariton of Valamo sometime early in the last century. It is basically Russian in spirituality (drawing largely from the papers of Theophan the Recluse) and should be helpful to someone interested in developing an interior life.
These things are perfectly fine for Catholics to read, one will not find anything heretical in them. Just be aware that there is definately a mystical aspect to most of this literature, some things are better studied under spiritual direction. We are all learners, our spirtuality develops over time.
There is a small but very vibrant
Russian Catholic church, and they will tell you that they are Russian Orthodox in Communion with Rome. This is their spirituality, drink deep of it if you are serious about learning of these treasures of our common Faith.
St Michaels’
Our Lady of Fatima
In the Theotokos,
Michael, that sinner