This plaintive choral work, possibly an incomplete fragment of an unfinished anthem, is essentially one long phrase building to a final resolution with just the right amount of dissonance. There are a number of fine recordings on youtube, but this performance is my current favourite. (It appears to be tuned in something close to a baroque pitch with A = 415, but I’m neither sure how accurate that estimate is nor how deliberate that specific choice was — those of you who know how to take Fourier transforms in practice can tell me how close I am.)
Edit: OK, thanks to an old answer here by user Lenoil (I love it how the Stack Exchange websites are stocked with competent experts able to answer so many questions; a pity there is no equivalent in mathematics), I could at least clip out the very first note in the file and let Mathematica compute the corresponding Fourier transform. There’s still a little vibrato which makes for inaccuracies, but here was the result from the opening “hear”:
Assuming (very generously to myself) that the second peak is the result of vibrato, I think this suggests an opening note very close to 245Hz. The piece itself is in C (minor) and opens on a middle C. Assuming (equal temperament) an A = 415 tuning, the resulting middle C should in fact be approximately
Make of that what you will (probably not so much, I imagine).