This is a re-typeset copy of the original (1961) book, revised with reference to the 1987 edition, with corrections to any errors I have found, and modification to any formatting I found confusing. Page numbering, line formatting, and font have been otherwise, faithfully followed. Referenced external texts have been copied from the referenced sources, and inserted after the main text. This was originally a pdf Ebook, with embedded audio, taken from the recordings reference, and indeed specially produced by Gael-Linn.The copyright of this book still belongs to Hodder and Stoughton, but permission to publish has been granted, see inside back pages, on the basis that they consider the work to be obsolete, and superseded, and so they have no further financial interest in it.