Happiness, the goal to which we all are striving is reached by endeavoring to make the lives of others happy, and if by renouncing the luxuries of life we can lighten the burdens of others.... surely the simplification of our wants is a thing greatly to be desired! And so, if instead of supposing that we must become hermits and dwellers in caves in order to practice simplicity, we set about simplifying our affairs, each according to his own convictions and opportunity, much good will result and the simple life will at once be established.
If you let go a little you will have a little happiness. If you let go a lot you will have a lot of happiness. If you let go completely you will be free.
Material objects give rise to physical happiness, while spiritual development gives rise to mental happiness. Since we experience both physical and mental happiness, we need both material and spiritual development. This is why, for our own good and that of society we need to balance material progress with inner development.