At first, I would like to point to that in which the mistake is in the thinking, actually. Something peculiar has formed with references to the way in what way the human being positions himself to his concepts and ideas today. He does not think in most cases that concepts and ideas, even if they are well founded, are only tools to judge reality, as it faces us individually in every single case. The human being believes if he has formed a concept that this concept is immediately applicable to the world. The just characterised misunderstandings are based on this property of modern thinking. One does not consider today that a concept can be quite right, but that one can apply it quite wrong.
I want to explain this with maybe absurd examples that could occur in life. Anybody could have the indeed entitled conviction that sleep is a good remedy. If this mental picture is not correctly applied in the single case, such a thing can happen that somebody makes a visit somewhere; he finds an old man who is indisposed, is ill in this or that way. He tells his knowledge saying, I know that a healthy sleep is good. When he leaves the room, one can maybe say to him, well, did you not notice that the old man is sleeping perpetually? Alternatively, it can happen that another has the view that walking, movement is exceptionally healthy for certain illnesses. He advises this to somebody. The somebody has only to argue: you forget that I am a postman.
I want only to indicate the fundamental with it: the fact that one can have right concepts that, however, these concepts become only useful if you apply them correctly in life.
Source: Rudolf Steiner – GA 66 – Human Soul and Human Body Considered Scientifically and Spiritual-Scientifically – Berlin, 15 March 1917