When thinking, the spiritual researcher does not only ask himself whether the thought is logical, but makes sure it conforms to reality. That is his criterion for adopting a thought. He only accepts an idea when this idea is in line with reality.
Source (German): Rudolf Steiner – GA 324a – Die vierte Dimension – Dornach, April 7, 1921 (page 202)
Previously posted on September 26, 2016