When this course of lectures was first started the division line between natural and revealed religion was much more strongly marked than it is at present. Natural and revealed religion differ only in the point of view. Natural religion has to deal with all religion that exists, while everything which touches the sympathies is classed under revealed religion.
The true question is of the reality and validity of religious sentiment. All religious forms are necessarily and confessedly symbolic; they are representative of something other than what their mere outer appearance would suggest; thus it is only the spirit of the heart and soul which gives the Church and Liturgy their true signification. Until the symbols are explained, they serve merely to hide their true meaning. Thus the relation of man to the infinite and unknown of life must be understood. Man, living in the known world, can tell nothing of the infinite, but upon coming to the blank wall of the unknown, without being able to affirm anything, he feels that there is something behind it, which, however, he can define only by negatives.
This cannot satisfactorily explain the resistless influence of religious force. It is better to think of this feeling as the gradual fading away of our known limits and the revealing of a vast futurity. The adding to religion of what we know is thus the universalizing as well as the spiritualizing of our world.