In his day, no preacher in the Highlands was as attractive or well regarded as the Reverend Murdoch Campbell, the author of 'Gleanings of Highland Harvest', 'The Loveliest Story Ever Told', 'Memories of a Wayfaring Man', and 'Wells of Joy'. His Diary is of interest for his life and times, but also as one of the few documented accounts of 20th century Christian mysticism, extending across forty-one years. Its value is not only historical or academic; such a record of fellowship with God is for many beyond price. Interest in mysticism is flourishing, but relatively few commentators look at the Biblical mysticism of Evangelical Protestants. Here the Diary speaks for itself, while a Preface, Biographical Notes, and footnotes add background information and comment. Mystical knowledge of God is not in competition with either faith or 'love for one's neighbour as oneself', but is an added privilege, granted to few. It represents a challenge to well-substantiated ordinary assumptions concerning what can be known, both naturally and, for believers, spiritually. Yet this Diary shows how such contact with God leads beyond ordinary experience to the suburbs of Heaven.