We spend our entire lives acquiring "stuff", items people measure in terms of wealth or a kingdom if you will. But ultimately you could be the richest man alive with everything you could have ever wanted and in the end when your gone, it'll be divided up by anyone and everyone, and all that you'll have been will be gone.
When you measure your life, your kingdom, in the things that you do, you leave behind so much more. Einstein didn't leave behind a kingdom in the lord of the rings sense of the word, but in the sense that his theories his "kingdom" will live on for countless ages.
It's what we do that we'll be remembered by, not what we had. Sometimes that thought scares me more then anything for when I die who will remember the kingdom I left behind? If that kingdom is a single story home in the mid-west filled with "stuff", then I'm not leaving behind anything at all. Living my life only to be forgotten after a generation, much like my ancestors before me...
I can only hope that some day, the kingdom I build through the things that I do will be one that will live on long after I am gone, if not through my own hands or ideas, at least through what I teach my children some day.