Patanjali was a Hindu master who lived sometime between BC400 and 400AD. This 1953 translation is by the Californian Vedantist, Swami Prabhavananda, and Christopher Isherwood - well after saying goodbye to Berlin! There is a superb commentary, which is the purpose of the book.
The book is a treatise on Yoga, divided into aims, practice, powers and liberation. The Swami has a deep understanding of Catholicism (read also his Sermon on the Mount according to Vedanta) and his commentary is spot on for westerners. He explains mind control, purification, non-attachment and the art of meditation and contemplation. There is nothing that would offend Christians and any attempt to use the physical powers of Yoga is discouraged. Read the work, pick a few Christian images, concentrate and remove all the cloying stains of Maya, the illusory world of space and time. This should be obligatory reading in school religious courses; it cannot help but transform your outlook on life.
Of course the depth of spiritual achievement depends on the time available for meditation and contemplation, but even a small amount of time each day devoted to study of the book brings benefit, and one can take on trust the Swami's beautifully clear statements about those things that only the monk has time to discover.