Why does Biodynamics focus on ‘The Etheric Formative Forces?’

In Part 2 of my reorganisation of the Agriculture Course I trust it is very clear that a good 25% of the Dr Steiner’s Agriculture course was dedicated to the practical reality of the four physical activities of Cosmic Forces, Cosmic Substance, Earthly Forces and Earthly Substance. In contrast to this we find Dr Steiner making only a passing comment to the existence of the etheric forces in the second lecture.