"By Water, Wood, and Hill"

I stumbled upon this letter (on theonering.net) to Peter Hastings from J.R.R. Tolkien describing Tom Bombadil, my favorite character. (Emphases below are mine, as are paragraph breaks; it's a long chunk of text) 

“I don’t think Tom needs philosophizing about, and is not improved by it. But many have found him an odd or indeed discordant ingredient. In historical fact I put him in because I had already ‘invented’ him independently (he first appeared in the Oxford Magazine) and wanted an ‘adventure’ on the way. But I kept him in, and as he was, because he represents certain things otherwise left out. 

I do not mean him to be an allegory – or I should not have given him so particular, individual, and ridiculous a name – but ‘allegory’ is the only mode of exhibiting certain functions: he is then an ‘allegory’, or an exemplar, a particular embodying of pure (real) natural science: the spirit that desires knowledge of other things, their history and nature, because they are ‘other’ and wholly independent of the enquiring mind, a spirit coeval with the rational mind, and entirely unconcerned with ‘doing’ anything with the knowledge: Zoology and Botany not Cattle-breeding or Agriculture. Even the Elves hardly show this : they are primarily artists. 

Also T.B. exhibits another point in his attitude to the Ring, and its failure to affect him. You must concentrate on some pan, probably relatively small, of the World (Universe), whether to tell a tale, however long, or to learn anything however fundamental – and therefore much will from that ‘point of view’ be left out, distorted on the circumference, or seem a discordant oddity. The power of the Ring over all concerned, even the Wizards or Emissaries, is not a delusion – but it is not the whole picture, even of the then state and content of that pan of the Universe.”