Do enough medicine and you'll see just how wrong this is. Every medical issue leaves damage on your body. Mostly very small. Even fractures, the example often given, yes, a broken bone grows back stronger ... and less flexible, more brittle and heavier, more calcified, with less blood going through it a fact it will not cease to remind you off once you turn 55 or so.
Not to be misunderstood, that Nietzsche quote was a sarcastic comment on some strange lines of thought one can find in the anti-vaccination fringes.
Another one is 'God wills it' and another one is, it's 'natural' or 'pure'.
As an extreme, you can find that strange mix of sentimental almost pseudo-religious nature enthusiasm, magical thinking and barbarism in National Socialism.
They were obsessed with the healthy Aryan body, albeit its rulers themselves for the most part not exactly the most outstanding specimens.
Metaphors of health, disease, and parasitism in the racial corpus permeate the whole ideology like metastasized cancer.
Of course, the Reich just needed healthy soldiers, ruthlessly against the weak amongst themselves and the enemy.
Do enough medicine and you'll see just how wrong this is. Every medical issue leaves damage on your body. Mostly very small. Even fractures, the example often given, yes, a broken bone grows back stronger ... and less flexible, more brittle and heavier, more calcified, with less blood going through it a fact it will not cease to remind you off once you turn 55 or so.