I attended a technical talk today that I enjoyed very much. The speaker was showing a scientific result that was very practical and useful.
Yet at the same time, the mathematical theory underlying the technique was also very beautiful and elegant. And that is not usually the case.
Most of the time, people invent very practical things that are not at all formally elegant. The invention gets the job done, but in a way that is very messy and unaesthetic.
But every once in a while I encounter a beautiful and simple theoretical framework that also produces a truly practical result. And when that happens, it takes my breath away.
And it reminds me, all over gain, why I love math so much.