One hears it quite often said, mostly in Central Europe, but perhaps in Western Europe too, that there is only one health, but a multitude of diseases. This statement, which many believe to be correct, cannot be upheld in the light of a genuine knowledge of the human being. Because man is so individual, so particularly formed, that everyone, every child, already has a very specially suited health. We can therefore say that there are as many states of health and diseases as there are people. This reminds us of the necessity to continually focus on understanding the individual nature of man.
Source (German): Rudolf Steiner – GA 303 – Die gesunde Entwickelung des Menschenwesens -Eine Einführung in die anthroposophische Pädagogik und Didaktik – Dornach, December 28, 1921 (page 100)