Well, yes, but the invertibility is conditional.
Compassion is easier with a concrete person for a target. As is... idk. There's probably some (respect? romantic love? Loyalty?).
Hate is easier with a diffuse target. As is, say, idolizing love, disgust, contempt, superiority, etc.
The invertibility isn't in that you can flip "harder" to "easier" and then have it make just as much sense. You have to change the emotion too, which signifies that there is a categorization of emotions: useful!
If you insist that this is invertible wisdom, then I must say you are misapplying the heuristic.
Hate is easier with a diffuse target.
Depends. A klansman may find it easy to hate "niggers" but much harder to hate his black neighbour. A literary critic who values her tolerance may it find difficult to hate an abstract group but can passionately hate her mother-in-law. I am not sure whether the difference stems from there being two different types of hate, or only from different causes of the same sort of hate.
Here's the new thread for posting quotes, with the usual rules: