This is on a sign that I pass whenever I walk the north section of the Tom Taylor trail. I don't know about great, but thoughts do appear when walking. It's a great way to clear the mind, or mull over things.
Walking along the river, through the trees, listening to the ducks and geese, is the perfect place to think about writing, coming up with ideas for a story, or fixing a part that just isn't quite right.
It's a quote from Friedrich Nietzsche, it's just missing the word 'all' at the beginning.