This one is not quite a quote, but a parable of sorts, whose form, I've learned, was quite adapted from the original by the time it was introduced to me. Once in a while, a gem comes to me by way of my dad ...and this is one of them:
adaptation of the original by Loren Eiseley
There was a young man walking down a deserted beach just before
dawn. In the distance he saw a frail old man. As he approached the
old man, he saw him picking up stranded starfish and throwing them
back into the sea. The young man gazed in wonder as the old man
again and again threw the small starfish from the sand to the water.
He asked, "Old man, why are you doing what seems to be a waste of time?"
The old man explained that the stranded starfish would die if left
in the morning sun.
"But there must be thousands of beaches and millions of starfish!",
exclaimed the young man. "What does it matter?"
The old man looked down at the small starfish in his hand and as he
threw it to the safety of the sea, he said, "It matters to that one."
...I love that story.