Idea of the Holy

The Idea of the Holy: An Inquiry into the Non-rational Factor in the Idea of the Divine and Its Relation to the Rational by Rudolf Otto, translated by John W Harvey, 229 pages 

In this classic work, Otto attempts an analysis of the concept of "the holy" while simultaneously avoiding both the Kantian reduction of religion to ethics and the emotivist reduction of religion to feelings.  His task, therefore, is a rational exploration of the non-rational (not irrational) component of religion - the numinous, the "spooky", the "mysterium tremendum" or mystery which can only be approached with Pauline "fear and trembling".  For Otto, this represents the given object of the religious experience, with rational and moral content following later, filling out the concept.  The numinous is apprehended by use of a sense analogous to the aesthetic sense.

Unfortunately, despite Otto's insights into the nature of the experience of the numinous, he neglects to consider the manner in which a Numen which he acknowledges as personal might choose to disclose Itself, or, indeed, that a Numen which is supra-personal must disclose Itself.  The result is a purely naturalistic account prone to the same psychological reductionism Otto strove to avoid.