It is on these grounds that, in discussing the meaning and origin of an ancient Italian priesthood, I have devoted so much attention to the popular customs and superstitions of modern Europe. In this part of my subject I have made great use of the works of the late W. Mannhardt, without which, indeed, my book could scarcely have been written. Fully recognising the truth of the principles which I have {xiii} imperfectly stated, Mannhardt set himself systematically to collect, compare, and explain the living superstitions of the peasantry. Of this wide field the special department which he marked out for himself was the religion of the woodman and the farmer, in other words, the superstitious beliefs and rites connected with trees and cultivated plants. By oral enquiry, and by printed questions scattered broadcast over Europe, as well as by ransacking the literature of folk-lore, he collected a mass of evidence, part of which he published in a series of admirable works. But his health, always feeble, broke down before he could complete the comprehensive and really vast scheme which he had planned, and at his too early death much of his precious materials remained unpublished. His manuscripts are now deposited in the University Library at Berlin, and in the interest of the study to which he devoted his life it is greatly to be desired that they should be examined, and that such portions of them as he has not utilised in his books should be given to the world. Of his published works the most important are, first, two tracts, _Roggenwolf und Roggenhund_, Danzig, 1865 (second edition, Danzig, 1866), and _Die Korndämonen_, Berlin, 1868. These little works were put forward by him tentatively, in the hope of exciting interest in his enquiries and thereby securing the help of others in pursuing them. But, except from a few learned societies, they met with very little attention. Undeterred by the cold reception accorded to his efforts he worked steadily on, and in 1875 published his chief work, _Der Baumkultus der Germanen und ihrer Nachbarstämme_. This was followed in 1877 by _Antike Wald- und Feldkulte_. His _Mythologische Forschungen_, a posthumous work, appeared in 1884.