Franz Bardon is considered by many as the greatest adept of the 20th century.  A tireless worker for the light, he survived Hitler's concentration camps but died a victim of Communist persecution in 1958.  He left behind four legendary books which have become acknowledged classics of occult literature. 
The Practice of Magical Evocation is the second work in Bardon's opus, and thoroughly unique.  In magical terms, the book is a practical guide to the proper evocation of and communication with spiritual, magical and divine entities.  It is perhaps the only truly significant modern study of direct contact with the universal teachers.