Amazon.com description: Product Description: This challenging volume supports and extends the basis of Rudolf Steiner's philosophical and anthroposophical thinking. Students who are looking for a secure foundation in the spiritual realities spoken of by Steiner will find in this little book a continuing source of inspiration and encouragement. Rudolf Steiner had asked Unger to continue the work Steiner had done on a spiritual scientific theory of knowledge. This volume is the essence of that lifelong effort. Here Carl Unger writes on human nature and the I; natural and spiritual science; and the "philosophy of contradiction" with which we are continually faced.