The pleasures of philosophy, or wisdom (those of Reason), are alone true and pure; the pleasures corresponding to the two other parts of the mind are inferior; Love of Honour (from Courage or Energy), and Love of Money (Appetite).

The well-ordered mind--Justice--is above all things the source of happiness.

Apart from all consequences of Justice, this is true; the addition of the natural results only enhances the strength of the position.
In TIMAEUS, Plato repeats the doctrine that wickedness is to the mind what disease is to the body.

The soul suffers from two distempers, madness and ignorance; the man under passionate heat is not wicked voluntarily.

No man is bad willingly; but only from some evil habit of body, the effect of bad bringing-up [very much the view of Robert Owen].
The long treatise called the LAWS, being a modified scheme of a Republic, goes over the same ground with more detail.