Dumbledore's sister died her grave read this: "Where your treasure is, there will your heart be also." Matthew 6, a book and verse from the bible, says the same thing. ""Do not lay up for yourselves treasures on earth, where moth and rust destroy and where thieves break in and steal, but lay up for yourselves treasures in heaven, where neither moth nor rust destroys and where thieves do not break in and steal. For where your treasure is, there your heart will be also."

The circumstances surrounding the death of his sister help us understand. Dumbledore's greed (though cloaked with good intentions) for the most powerful of earthly treasures, the Deathly Hallows, ultimately led to his sister's death. Suffice it to say that Dumbledore's sister Ariana was one of the most tragic characters in the whole Harry Potter series. Her life was one of immeasurable hurt. And her need was the most basic need of those who are in pain. She needed love. Sacrificial love. Dumbledore failed her. He was incapable of fulfilling his duties to care for her while pursuing his ambitions for power. His failure which led to his sister's death helped Dumbledore to comprehend one of the other truths of Matthew 6, "No one can serve two masters" (Matthew 6:24). The pursuit of possessions of power, even for benevolent reasons, can ultimately only lead to death and ruin. As he puts it in his own words, Dumbledore understood that he, the most powerful wizard of his day, "Was not to be trusted with power."

Originally Posted by Gospel According to John 12

For where your treasure is, there also will your heart be.