Andy Letcher has indeed done some great research. His book offers many valuable new morsels of
information for shroom enthusiasts. His conclusions however are all too often skewed by what seems to
be a predetermined thesis, that is, that the use of psychedelic mushrooms is
essentially a modern phenomenon.
Letcher's delivery also smacks of intellectual arrogance. All too often he commits the very "crime" that he accuses other researchers of committing - fitting "facts" to his theory rather than assessing them on their own merit.
Shroom: A Cultural History of the Magic Mushroom is a worthwhile read, but be warned, you may find yourself getting a little angered by it. I did!