"The wise person is detached from all things;
that is why she is one with them.
Because she has let go of herself,
she is perfectly fulfilled."
This passage is about a special kind of detachment. If you were detached from some things but not all, you would be obsessive. If you were detached from all things but not yourself, you would be selfish. If you were detached from yourself but not from things, you would be without direction.
This passage is about the kind of detachment that enables you to regard all things and all people, including your own things and your own self, with equinamity. An attachment to a particular thing is like a wall that isolates you from everything else. Total detachment is total openness, from which connections can be made that do not cause isolation.
It takes courage to let go of your attachments. Without them, what would you have? According to this passage, you would have more than you imagine.