If we examine the trials and tribulations all over earth, we'll find they are rooted in human hearts. Covetousness, the desire to aggress and exploit, the longing to pilfer natural resources, the inordinate love of wealth, and other maladies are manifestations of diseases found nowhere but in the heart.
Every criminal, miser, abuser, scoffer, embezzler, and hateful person does what he or she does because of a diseased heart. So if you want to change our world, do not begin by rectifying the outward. Instead, change the condition of the inward.