Longfellow understood this business of tending to the 'temple' within:
Let us then labor for an inward stillness, An inward stillness and an inward healing, That perfect silence where the lips and heart Are still, and we no longer entertain Our own imperfect thought and vain opinions, But God alone speaks in us, and we wait In singleness of heart, that we may know His will, and in the silence of our spirits, That we may do His will, and do that only!
"Real happiness is not dependent on external things. The pond is fed from within. The kind of happiness that stays with you is the happiness that springs from inward thoughts and emotions. You must think of this now, while you are young. You must cultivate your mind if you wish to achieve enduring happiness. You must furnish your mind with interesting thoughts and ideas. For an empty mind grows bored and cannot endure itself. An empty mind seeks pleasure as a substitute for happiness." --William L. Phelps
"The happiest person is the person who thinks the most interesting thoughts." --Timothy Dwight