Onomatopoeia

The word onomatopoeia descibes other words which sound like their action e.g. buzz or murmur, but I am curious to know what on earth inspired this strange word. And why the inventor made it so damn hard to spell. Can anybody sugest an origin?

From my tatty old Oxford English Dictionary:

-ORIGIN late 16th cent.: via late Latin from Greek onomatopoiia 'word-making', from onoma, onomat- 'name' + -poios 'making' (from poiein 'to make').