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.
REVOLUTION, n. In politics, an abrupt change in the form of misgovernment. . . . the substitution of the rule of an Administration for that of a Ministry, whereby the welfare and happiness of the people were advanced a full half-inch.