A concept, an idea, a mental picture is real, as soon as one approaches the spiritual facts and beings, is nothing but an image, a photo which one gets in the physical world, we say of a tree. If one takes a photo of a tree from one side and a photo from another side, a photo from the third side — these pictures look different. However, they all are of the one and same tree. Only because one takes these photos from different sides one can receive a complete idea of reality. However, one does not like that today. One likes limited concepts. One wants to adhere to them. Spiritual science cannot do this. Spiritual science describes a matter from most different sides; it describes it once from one side and knows that it gives an one-sided picture only; then it describes it from a second side, from a third side, from a third viewpoint.
Indeed, what astonishes even more is the following. If one really wants to become a spiritual scientist, one has to be completely penetrated by the sentence that Goethe formed: between two contrary opinions, the problem is right in the middle. One must know not only — if one wants to know the truth of a spiritual being or a spiritual fact — what militates for it, but also what speaks against it.
The listeners who have frequently heard talks by me know that it is my habit from the spiritual-scientific attitude to not only say what militates for, but also what militates against a matter. In particular, I have the habit of doing this always if I hold talks about more intimate talks on higher fields of anthroposophy. That is why someone who peruses my writings not only discovers with which arguments one can found certain spiritual facts, spiritual beings, but also with which arguments one can disprove the things. Only thereby, one receives truthful experience.
Source: Rudolf Steiner – GA 72 – II: Anthroposophy Does not Disturb Any Religious Confession – Basel, 19 October 1917