IV. The Symbolism of the Building at Dornach II

The next forms would then perhaps be such that the ethereal forms would be these [sixth]. But it is not this ethereal form that comes to the fore, but rather what remains visible on the outside is this [the thick line], which in turn is a simplification, an essential simplification, so that if you just consider physical development, you go from a stage of 1-2-3-4 in complication, then in simplification. This is also really the principle of development in nature.