I am interested in the Essenes and really wanted to like this book.
Olivier claims that from Enoch (aka Hermes, Thoth, etc) just about every avatar (Buddha, Zoaraster, Mohammed, Jesus, etc.) was an Essene. For much of this book a nebulous whispy spirituality is presented and the fruits of all enlightment are known from Enoch only through the Essenes. Olivier should know that current thinking is that Quamram were probably not Essenes at all. In short, the fluffiness of this book (claims without substantiation), tells almost nothing verifiable about the Essenes.
What it does claim in detail would have been revealed by texts somehow not destroyed by the evil 'church of St. Peter' which somehow missed thosed texts. The evidence is neither from the Dead Sea Scrolls but from revelation spiritually to Olivier. These two extremes, non-specific bantering (in the spirit of I'm OK, you're OK, I'm spiritual, wheee) to specifics with no substantation leave no middle way (a term familiar to Buddhists).
On the back cover Manitara claims that 'Only techniques can liberate man..' But his writing is largely unspecific and borders on the style of creative fantasy. This seems like a marketing piece by Oliver. It leaves you unsatisfied enough to wonder what he might be holding back so you might make the mistake of spending more money and time for the same fluffiness.
There are other sources of information on the Essenes. But unfortunately there are no writings (that this writer is aware of) that can be considered authentically Essene. This includes this book or the works of Szekely. The Gospel Of The Holy Twelve is held up as an authentic Aramaic/Essene text but the reader will need to decide that for themseves.
You are better off sticking with sources based on Dead Sea Scroll texts. But keep in mind those writings are in no way guaranteed to be Essene. The Essenes are a great concept but unless more texts are found their legacy has been lost to history. What people are creating today and saying is authentic 'Essene' is at best creative re-construction (based on 'Essene Gospel of Peace' which is of unverified authenticity) and at worst imagination.