How does one make Bosch dull...? Let's ask Dr. Dixon...
Perhaps I'm being unfair to the author..., But I didn't much like this book, and so have given it up.
The book is full of a wide range of specifics regarding medieval chemistry, alchemy, proverbs, etc. etc., and if one is 'working' (as academics like to say) on a particular triptych, say (the chapters can be read more or less independently), then one will find much of use here -- though even then the book is not really properly footnoted or bibliographed for the needs of actual scholars.
But in all of this, Dixon utterly fails to bring out anything (as in 'nada', 'zip', 'zilch') of the haunting beauty of Bosch's extravagant paintings, and so offers little of real value for the general ('educated layman') reader for whom this series is presumably designed. (The Phaidon A&I 'Breugel', by contrast, is a fabulous book.)
The above is probably too harsh. There is a lot of interesting material here. But much of it -- discussions of medieval astrology, e.g., -- seems to be taken from handbooks and at second-hand, and so doesn't really rise above the level that the generally informed reader will already know... And fails to do so (that is, 'rise above'...) at great length...
Hence, informed, but rather surprisingly dull.