For those who want to expand their magick and use the time cycle of the Moon effectively, besides using the lunar light (Dark Moon, first quarter, Full Moon, last quarter) this is the book they are looking for about finding the right moment for a ritual or a physical action and secondly, for creating a talisman using the Moon energies.
Just like there is a division of 12 zodiac signs for the apparent movement of the Sun, there are 28 zodiacs of the Moon. These are positions of the Moon with a specific energy. We can perform a ritual at that time, relevant to the energy of the mansion. We can draw this lunar energy on an object or avoid performing a ritual that is against the energy of the mansion. Each mansion is favourable for certain things and unfavourable for other things.
This ancient type of magick has been neglected in our modern magickal world and it shouldn't be. The book is a very good and complete study on the subject. Its main source is Picatrix and he also draws additional information from Agrippa's books on Occult Philosophy and other sources. In the first pages, he starts by providing the information of how we can use the system of the lunar mansions and then we read about each of the 28 mansions independently. He also provides personal thoughts and there is an attempt to explain the properties of each mansion based on the interpretations of Ptolemy on the fixed stars that surround each mansion.
Then we have the interpretation of the lunar mansions in the natal chart and eleven appendixes on various subjects, which will be useful only to a small number of researchers. The book is well written, explains the system without needing further knowledge, although the advanced elections are quite tricky.
Read this article on the Lunar Mansions and if you want to work with them, buy the book.
Theurgy and Philosophy are two different methods which lead to the union with God.