Happiness and unhappiness are in the heart and spirit of each one of us: If you feel unhappy, then place yourself above that and act so that your happiness does not get to be dependent on anything.
The trouble is that my heart is loath to be without love even for a single hour. ... If you want to keep me forever, then show as much friendship as love, and more than anything else, love me and tell me the truth.
[On Peter III:] He did not have a bad heart; but a weak man usually has not.