Justice is conscience, not a personal conscience but the conscience of the whole of humanity. Those who clearly recognize the voice of their own conscience usually recognize also the voice of justice.
One should never direct people towards happiness, because happiness too is an idol of the market-place. One should direct them towards mutual affection. A beast gnawing at its prey can be happy too, but only human beings can feel affection for each other, and this is the highest achievement they can aspire to.
When you're cold, don't expect sympathy from someone who's warm.