Material happiness means to have good facilities for eating, sleeping, sexual intercourse and defense. Within this world, the materialistic person lives only for these four principles of sense gratification, not caring for the impending danger of death. After his father's death, a son tries to inherit his money and use it for sense gratification. Similarly, one whose son dies tries to enjoy the possessions of his son. Sometimes the father of a dead son even enjoys his son's widow. Materialistic persons behave in this way. Thus Śukadeva Gosvāmī says, "How wonderful are these pastimes of material happiness transacted by the will of the Supreme Personality of Godhead!" In other words, materialistic persons want to commit all kinds of sinful activities, but without the sanction of the Supreme Personality of Godhead, no one can do anything. Why does the Supreme Personality of Godhead permit sinful activities? The Supreme Lord does not want any living being to act sinfully, and He begs him through his good conscience to refrain from sin. But when someone insists upon acting sinfully, the Supreme Lord gives him the sanction to act at his own risk (mattaḥ smṛtir jñānam apohanaṁ ca (BG 15.15)). No one can do anything without the sanction of the Lord, but He is so kind that when the conditioned soul persists in doing something, the Lord permits the individual soul to act at his own risk.
According to Śrīla Viśvanātha Cakravartī Ṭhākura, sons always outlive their fathers in other planetary systems and other lands in this universe, especially on Svargaloka. However, on this planet earth a son often dies before his father, and the materialistic father is pleased to enjoy the possessions of his son. Neither the father nor the son can see the reality—that both of them are awaiting death. When death comes, however, all their plans for material enjoyment are finished.