Language is amazing. It constantly evolves, and is full of rich complexity. It is so complete, and yet so incomplete at the same time.
One of the things that I find most amazing is in the development of sounds. Two groups who live in slightly different parts of the world, speaking the same language, can end up sounding nothing alike. We know, for example, that French and Spanish come from the same Vulgar Latin, but they sound so different from one another.
What's amazing, though, is that they differ from Latin in many of the same ways. The word "quickly" in Latin is celeriter, but in French it is rapidement, and in Spanish, rapidamente. Both made the same change to the stem root word (celer -> rapidus) but also made the same change to indicate an adverb (-iter -> -mente).
The difference is even more drastic when words are shared across language families. The name of Tokyo, for example, literally means "eastern capital" in standard Japanese. In Mandarin Chinese, this is translated literally; Tokyo is called "Dongjing." The crazy part is that both "Tokyo" and "Dongjing" derive from the same old Chinese root word while sounding nothing like each other, except in ways that are significant mostly to professional linguists. Same with the Japanese and Mandarin names for China: Chugoku and Zhongguo, both meaning "Middle Kingdom," and both deriving from the same source (though there's a whole long story behind that one).
If you share this love of language, please feel free to express it here!