Wilhelm Schmidt-Biggemann 
Philosophia perennis [PDF ebook] 
Historical Outlines of Western Spirituality in Ancient, Medieval and Early Modern Thought

The study features the five most important and most efficacious themes of Western spirituality in their ancient historical origins and in their unfolding up to early modernity: Divine names, Microkosmos-Makrokosmos, theories of creation, the idea of spiritual spaces, and the concepts of eschatological history.