And if we ask how are we to know where our hearts are, the answer is just as simple - everything which hinders us from loving God above all things and acts as a barrier between ourselves and our obedience to Jesus is our treasure, and the place where our heart is.
I class the principle of moral feeling under that of happiness, because every empirical interest promises to contribute to our well-being by the agreeableness that a thing affords, whether profit be regarded.