Think of the marvelous structure of the femur, of the bone which bears the whole body. Its construction is such that the maximum amount of strength is produced with the minimum amount of substance. No engineer could create such a wonder-structure. In comparison with the physical body, the astral body — the seat of passions and desires — is rudimentary and crude.
The physical world is the expression of wisdom incarnate, divine wisdom.
Source: Rudolf Steiner – An Esoteric Cosmology Lecture IV: Involution and Evolution – Paris, 28 May 1906
Source (German): Rudolf Steiner – GA 094 – Kosmogonie – Parijs, 28 mei 1906 (p 35)