Of course, when I say that human nature is gentleness, it is not 100 percent so. Every human being has that nature, but there are many people acting against their nature, being false.
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.