Karl Koenig meditated intensely on the 52 weekly verses of Rudolf Steiner's Calendar of the Soul. During his time in internment on the Isle of Man, he made these 52 naive, artistic sketches to accompany each verse. This is a wonderful way to experience an important spiritual tool.
There is also a separate book by Karl Koenig, The Calendar of the Soul, which is a complementary text commentary on Steiner's Calendar.