To what is Goethe refering in the following: What you have inherited from your parents, earn over and over again for yourself or it will not be...

I think that Goethe is suggesting that individuals have
and must use their own sense of freedom and autonomy in defining their identity.  This
is a highly Romantic idea, in which Goethe believed.  Individuals cannot expect their
past to fully define their own sense of self.  The Romantic thinkers were strong
advocates of self definition, of utilizing one's freedom to break the shackles of social
conformity.  Goethe is arguing this point.  What has been inherited from one's parents
is good, but if one simply lives their life through this, one is not living their own
life, but rather the life of someone else.  Reflect on it in this manner.  If someone
inherits a large sum of money and they don't do anything to add to it, then they are not
living their own life, but the life someone else has given to them.  Their life, their
sense of being, is not their own.  On this level, Goethe is saying use what others have
given you, but stand on your own and carve out your own identity so that one's life is
one's own and not the extension of someone else's.