Full Idea
Rational beings cannot posit themselves as effective individuals without ascribing to themselves a material body and determining it in doing so.
Gist of Idea
Effective individuals must posit a specific material body for themselves
Source
Johann Fichte (The Science of Rights [1797], p.87), quoted by Ludwig Siep - Fichte
Book Reference
'A Companion to Continental Philosophy', ed/tr. Critchley,S/Schroeder,W [Blackwell 1999], p.64
A Reaction
To be free entails a belief that one is 'effective', and a body is our only concept for that. This seems to be a transcendental proof that the body must exist, which is a neat inverted move! The Self sustains the body, for Fichte.