Look what I found in an old blog post of mine from 2018. This is the explanation we´ve been looking for!
>>>Steiner's lectures contain another very strange speculation: the claim that the Buddha went to Mars (or perhaps the “Mars sphere”, but Steiner does seem to mean the literal planet Mars) in order to carry out a Martian version of the Mystery of Golgotha (!).
>>>However, Buddha was never literally crucified (since the Martians seem to be ethereal beings, an actual crucifixion might have been impossible to arrange anyway), but rather sacrificed himself by sending out love and kindness to a planet the inhabitants of which were extremely aggressive.
>>>Apparently, this kind-hearted act has soothed the conflicts among the Martians, making it easier for human souls to pass through the planetary sphere of Mars during our cosmic sojourn between two earthly existences...
>>>I admit that this mutant Buddha legend is somewhat difficult to take seriously!
