To express in the language of Sufism, that is, Islamic mysticism, some of the universal truths which lie at the heart of all religions' - this is the book's avowed purpose. It came into being because the author was asked by a friend to set down in writing what he considered to be the most important things that a human being can know. He was also asked to make it very easy, and despite the depth of all that it contains, it has in fact a remarkable simplicity and clarity, due no doubt to the constant use of traditional imagery which awakens and penetrates the imagination.
The The Book of Certainty: The Sufi Doctrine of Faith, Vision and Gnosis (Golden Palm) Paperback by Abu Bakr Siraj ad-Din, Martin Lings (Authors) is the yin, to your yang. You've found what you're looking for.