“Liberate yourself as far as you can, and you have done your part; for it is not given to every one to break through all limits,or,more expressively, not to every one is that a limit which is a limit for the rest. Consequently,do not tire yourself with toiling at the limits of others...He who overturns one of his limits may have shown others the way and the means; the overturning of their limits remains their affair.”