Someone once likened Paradise Lost to a great cathedral that no one visits. Of course academics and students do read Milton, but I suspect that - when it comes to the average poetry enthusiast - old Milt is off limits. The same might be said of the average horror fan and the 'classics' of the genre. Lovecraft, yes, and we'll get to him later. But Blackwood - like Machen - is known to lovers of supernatural fiction thanks to a handful of much-anthologised stories.
One problems is that Blackwood wrote a lot of mediocre stuff during a very long career. Indeed, he wrote so many stories that even he was unsure how many he'd produced. Born in 1869, this contemporary of M.R. James lived long enough to appear on post-war BBC television before dying in 1951. But his best-known stories were written before the First World War. 'The Wendigo' and 'The Willows' are highly praised by virtually all experts in the field. 'The Wendigo' has inspired at least two films.
A few other tales occasionally emerge from the fog of obscurity to take their place in anthologies - 'The Glamour of the Snow', 'The Damned', 'The Other Wing', 'An Empty House', 'Ancient Lights'. And the John Silence stories - uneven though they are - rightly occupy a significant place in the history of the occult detective sub-genre. But most of Blackwood's stories are - like his novels - neglected. But Blackwood remains one of those writers who are admired from a distance by most fans of the weird tale.
It's not hard to see why. As Lovecraft remarked, Blackwood was strong on ideas but could be very poor on execution. His laboured prose style is slightly reminiscent of Henry James, in that both seem determined to immerse the reader in a warm soup of words rather than simply state what's going on and why. If reading M.R. James is like a leisurely stroll through shady undergrowth, reading Blackwood is often like swimming through treacle.
Much of the problem is down to fashion. Blackwood began writing long before the terse, journalistic style of Hemingway and his many imitators transformed popular fiction. But he did himself no favours by constantly struggling to express ideas that are inherently difficult to put into a story because they seem more suited to mystical musings - hence a tendency to ramble and digress.
In addition, Blackwood's attitude to supernatural forces was pantheistic and owed much to Eastern thought. Nature, in his world, is imbued with great power but is also 'beyond good and evil', so the conventional confrontations and resolutions of the modern horror story seldom apply. Thus in 'Ancient Sorceries', the best of the John Silence tales, there is no sense of evil despite the over theme of the witches's Sabbat. Instead there is erotic excitement and even regret that the timid hero doesn't throw in his lot with the witches.
But for all its faults Blackwood's best work belongs on the shelf next to the other greats. If you can immerse yourself in 'The Willows' or 'The Wendigo' you will not regret it. Yes, they are rambling tales and take a long time to get going. But the imagery, once it arrives, is immensely powerful and sticks in the mind. When reading Blackwood you get the feeling that you are in touch with a truly original and complex mind (and, it might be added, a thoroughly decent human being).
For my money the best introduction to Blackwood's work is a paperback, the Dover Best Ghost Stories edited by E.F. Bleiler. Second-hand editions are relatively cheap. It's also available for Kindle. More expensive hardback collections are available, notably the excellent volumes from Tartarus Press, though these can be very pricey.