What others did in the past influences what we do today. What is done today will influence what goes on in the future. It's like dominoes: stand them on end and place them in a line - one after another - and if the one at the beginning of the line is pushed over, all of them will fall down.
We all leave legacies. And each legacy is different because everyone is different. We seldom realize that we actually leave two different types of legacies. Most of the time we think of leaving a legacy of valuables: money, stocks, property, insurance, vehicles, jewelry - things that have monetary value.
But we rarely think of the legacy we leave that has eternal value - a value that has moral and spiritual influence or impact on the lives of others. Whether or not we realize it or want to admit it, we cannot not influence or impact the lives of others.
The writer of Psalm 71 was very conscious of the spiritual values he would leave behind. "Even when I am old and grey," he wrote, "do not forsake me my God, till I declare Your power to the next generation, Your mighty acts to all who are to come."
In the preceding verses he recalled the goodness of God in his life: "You are my refuge, my rock, my fortress, my hope, my confidence, my teacher, my Savior." God had been with Him, had honored and protected him and made his life worthwhile. He wanted others to know this God.
So, he asked God to spare him so he could share His Word.