A friend gave me this book years ago and I've only just cracked it open and realized how great it is. It's a nice compact volume which contains translations of St. Athanasius' On the Incarnation and also important theological writings of St. Gregory Nazianzen and St. Gregory of Nyssa. Its appendix also includes numerous important documents, including St. Cyril's 12 anathemas, the Tome of Leo, and the anathemas of the Fifth Ecumenical Council. It seems to me like an ideal introduction to the Fathers. So far I've On the Incarnation and I'll start on St. Gregory anon.