Keeping a spiritual diary is a practice that has often appeared wherever puritan piety is found. John Coffey and Paul C. H. Lim in the The Cambridge Companion to Puritanism describe the early Puritans in this way: "They prescribed a demanding regime of personal devotions, including godly reading, psalm-singing, prayer, fasting and spiritual meditation. They recommended practices of self-discipline, including keeping a spiritual diary and private covenanting." Isaac Ambrose in his Prima: The First Things in Relation to the Middle and Last Things, published in 1674, emphasised the importance of a spiritual diary and gave an example from his own. Thomas Goodwin found the practice helpful in his seven year struggle for personal assurance - during which time he was "intent on the conviction God had wrought in him, of the heinousness of sin, and of his own sinful and miserable state by nature; of the difference between the workings of natural conscience, though enlightened, and the motions of a holy soul, changed and acted by the Spirit, in an effectual work of peculiar saving grace. And accordingly he kept a constant diary." An excellent post on Puritan Diary keeping is here. I wonder if it is significant that in the past they kept private diaries and today we maintain public weblogs?
It was also a feature of later piety. Jessie Thain's Diary is a good example. John Macdonald of Ferintosh - the apostle of the North - writes as follows.
'Among the many omissions of my past life [he was c.36] which I have to lament, that of not keeping a diary, containing some account of the Lord's dealing with my soul, and of the work of my ministry, is not the least. I was chiefly prevented from this by a false humility, and was not thinking anything done in me or by me worthy of being recorded; and as reckoning myself so far behind those who usually kept such diaries that it would be presumptuous on my part to attempt anything of that kind. I now find, however, that this was a mistake, and I have no doubt that Satan was at the bottom of it; for if the Lord wrought in me and by me in any measure, however unworthy I am -- and none is more so, as He knows, on the face of the earth -- His work deserves to be recorded, and some account of it might be serviceable to myself, useful to others, and conducive in some measure to His glory. I would, therefore, in future endeavour to keep some account of my labours, with anything in my own soul, in providence regarding me, or in my success in the vineyard, which may be deserving of notice. And I begin with this year (1816).'