Body I am throughout, and nothing besides; and soul is merely a word for a something in the Body.
Body is one great reason, a plurality with one sense, a war and a peace, a flock and a herdsman ...
There is more reason in thy Body than in thy best wisdom. And who can know why thy Body needeth thy best wisdom?
[Nietzsche, Thus Spake Zarathustra I, 'Of the Despisers of the Body']
The idea of the Body as a macrocosm and microcosm is an essentially Classical idea; it appears in the anything from the 'Body Politic' of the Ancient Pagans, to the totalitarian 'Corporate State'.
It also appears in Nietzsche's philosophy on every level; the individual's 'soul', to Nietzsche, is like a complex political State, where the fundamental fact is Power - the Will to Power.
This is true not only of society at large, but of the Cosmos as a totality - all is Will to Power.
This clasical notion was revived, of course, in the Renaissance; but in the Enlightenment it was challenged by the contrary idea of the 'Contract'.
In this opposition, life is not down to the Body, and the Organic, but down to the Contractual.
This latter notion has triumphed today, for the time being, with Capitalist Democracy and its charters of 'human rights' etc.,
Many of the Romantics of the late 18th and 19th century, violently rejected this middle-class ideal of the Contract, and Nietzsche was certainly in agreement with those Romantics on this issue - hence his promotion of the Body.