The Secret Doctrine - H.P. Blavatsky

I was curious if anyone has read this book. I picked it up in local used bookstore in the freemasonry section. I don't know if it actually has anything to do with freemasonry, if anything maybe the founding beliefs/mantras. It claims to provide a synthesis of religion, philosophy, and science as well as the understanding of the underlying fabric of reality (holism). Anyway if any of you have heard of this book or even read it please give me your feedback.