Conversation so far:
Who did Rudolf Steiner work with?
Rudolf Steiner's closest co-worker from 1902 onwards, and later partner for life, came to be Marie von Sievers
What stands out about Rudolf Stainer?
At a Foundation Meeting for Anthroposophical Society members held at the Dornach center during Christmas 192, Steiner founded a school of Spiritual Science.

Question: When did he founded this school?
Self-contained rewrite: When did Rudolf Steiner found the School of Spiritual Science?