I just committed to writing two entries for the very exciting upcoming JRR Tolkien Encyclopedia for Scholarship and Critical Assessment, and since one of them is on Old High German, I was going over my OHG primer last night. (By last night I merely mean that it's now after midnight, b/c after watching House, M.D., and going over the OHG, I stayed up even further to read ... *gasp* ... the newest Harry Potter book.) Maybe another blogpost will discuss Harry Potter and Tolkien and magic and the impressionability of children and such, this one's about Proto-Indo-European (PIE), or just Indo-European.
Right, well, those of you who are left probably know what it is, but for the internet initiate who just hasn't learned to click away fast enough, it's the *language that must have existed in order to explain the regular patterns of relationships between the Celtic, Germanic, Slavic, Romance, Persian, and other languages (the Indo-European family). It is a unique type of delight for an amateur (for now) philologist to see two words as different as 'hostile' and 'guest' and know that they came from the same root. (The common element is 'stranger'. Ironic, isn't it, that it was the Germanics that assumed a friendly connotation, while the Latin assumed the stranger was an enemy.)
So you have a proposed (hence the asterisk) form that would have looked (had it ever been written down in the Latin alphabet) something like *chost I suppose, where the 'ch' means the sound in the Scottish word loch, not the sound in English 'chest'. From here, the Latins lightened it to host plus a Latin ending ... hence hostis, 'enemy'. The Germanic tribes (all still speaking the same common tongue at this point) tended to turn the 'ch' sound from PIE into a 'g', and a's into o's, so they started pronouncing it gast. And in fact, that's still the modern German word for 'guest'. The reason the English word is different is that the Saxons who migrated to Britain changed the vowel further because of the letter 'i' in the suffix that used to be there but which is now gone even though its effect (i-umlaut) remains. It's all so wonderfully complicated.
So you have one type of philological fun, which is comparing cognates in different languages (let's call this horizontal), but you also have the fun of tracing one word through its history, with change after change in spelling and pronunciation, and perhaps even in meaning, until it's hardly the same word anymore (this would be vertical). When you look at that word, and you see in each letter all the versions that have gone before it--each consonant and each vowel seeming to recall its immediate ancestor--and what's more, when you use that word fully intending in one fell swoop several of the various meanings and nuances it had along the way (the more the better), as if having a little inside joke with yourself--if all this comes naturally to you, then you're probably a born philologist. And probably crazy, too, but that's not for me to decide. Just to relate.