A feeling of hatred directed at another is very real, and for one who can see in the spiritual world, it is much more potent than hitting him with a stick. Although the terrible thing does not take place right before our eyes, yet it is so.
Source (German): Rudolf Steiner – GA 56 – Die Erkenntnis der Seele und des Geistes – Berlin, 12 December 1907 (page 144-145)
Anonymous translator
The great Rudolf Steiner Quotes Site 