Hello all! I'm back from many travels, which I shall surely write on in the coming days. In the meantime, though, here is a post that is not about travel.
An interesting pattern is seen in the English language in the pattern of "here"/"there"/"where," "hither"/"thither"/"whither," and "hence"/"thence"/"whence", wherein h- indicates presence, th- indicates distance, and wh- indicates inquisition (the wh- prefix is of course seen in myriad other examples). As is common with English, one of the more interesting things about this pattern is the exception to the rule. "That" and "what" both fit into the same pattern (that is over there, but who knows whither is what?), but in there is no matching third part. The present partner of "that" is "this," rather than "hat." English is not a language with any fear of homonyms, so I can't imagine that the sole factor in this is the existence of "hat" as in headwear.
The plural forms of the "that" set fall even further from the pattern, being "these"/"those"/"which."* It all leaves one to ponder, whence came these pronouns, and what shall we do about them? Whither is our language going, and how will we get there? And of course, why? Well, I can be sure that the answer isn't "thy."
*It could also be argued that "which" fits in better with "this"/"that" than does "what," but only if you're a real spoil-sport.