Der Geist wird erst frei, wenn er aufhört, Halt zu sein.
The spirit becomes free only when it ceases to be a support. [Kaiser/Wilkins]
The spirit only becomes free at the point where it ceases to be invoked as a support. [Hofmann]
The aphorism seems to be addressed to someone who is looking to become a free spirit, and it seems to be saying that you can't be a free spirit if you are all the time calling yourself a free spirit and trying to be one, and coming up with definitions of free spiritedness, otherwise turning it into a mechanical posture. To be a free spirit, you have to forget. It would be interesting to translate Halt here as "prop," because this would give us both the idea of propping up (supporting), but also the idea of a stage property, a mock-up of something real used in performances. A prop gun doesn't fire, and an idea of free spiritedness used as a prop is not emancipating nor is the spirit free.