I love prime lens. They are small, sharp, and by removing a step to think about - no zoom - they let you think more of that actually is going to be in the picture. ( Although this may not be true in general, only in my case. )
But primes can become serious restraints when you encounter the unexpected. In this case, a monastery, sitting within the clouds, with families of monkeys admiring the astonishing nothingness.
It takes too long to switch to the zoom lens, or to switch to another prime, which will eventually lead to missed moments. In my case, a perfect image of a monkey drinking from a bottle, with a reflection of it in a pool of water. By the time I switched to a longer lens, that moment was gone.
I still had the chance to create this one, which I'm quite glad for; but the lesson is learnt: when you don't know what to expect, keep the zoom lens on.