Arthur Edward Waite 
Hidden Church of the Holy Graal [PDF ebook] 
Its Legends and Symbolism; Considered in Their Affinity With Certain Mysteries of Initiation and Other Traces of a Secret Tradition in Christian Times

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. If deeper pitfalls are laid by anything more than by the facts of coincidence, it is perhaps by the intimations and suggestions of writing which bear, or are held to bear, on their surface the seals of allegory and, still more, of dual allusion; as in the cases of coincidence, so in these, it is necessary for the historical student to stand zealously on his guard and not to acknowledge second meaning or claims implied, however plausible, unless they are controlled and strengthened by independent evidence. Even with this precaution, his work will remain anxious, for the lineal path is difficult to find and follow. Perhaps there is one consolation offered by the gentle life of letters. In matters of interpretation, if always to succeed is denied us, to have deserved it is at least something.<br><br>Among our aids there is one aid which arises from the correspondences between distinct systems of allegory and symbolism. They are important within their own sphere; and it is by subsidiary lights of this nature that research can be directed occasionally into new tracks, from which unexpected and perhaps indubitable results may be derived ultimately.