In relation to obtaining knowledge of the human being nowadays, it must be said, that it is as if people attempt to understand how a watch works, by only looking at it from the outside. One can learn how it indicates time by looking at it, one can also get to know whether it is made of gold or silver, but one cannot become a watchmaker by observing it from the outside. What we currently call biology, physiology or anatomy, is still only knowledge obtained by way of observing the human being from the outside. A true understanding of human nature will only arise through observing body, soul and spirit. And only then can the human being be treated according to knowledge of body, soul and spirit.
Source (German): Rudolf Steiner – GA 303 – Die gesunde Entwickelung des Menschenwesens -Eine Einführung in die anthroposophische Pädagogik und Didaktik – Dornach, January 2, 1922 (page 199)
Translated by Nesta Carsten-Krüger