I think it means, that through the bad things, you discover the good ones. For example, by being in ugly physical shape you discover what is a beautiful physical shape; or in abusive relationship you discover value of caring relationship. Also, so called truth, the objective things in reality, for example what feelings and objects constitute yourself.
Notice the emotion and it’s cause, avoid the cause or engage in the cause purposefully ?
I don’t like the “hollower”, emptier", I would use “clearer”.
Too bad I can’t like my own comment haha 