What are all those influences that are about us in the atmosphere, that keep playing over our nerves like fingers on stringed instruments, and call forth now a sweet note, and now a wail--now an exultant swell, and anon the saddest cadence?

"What are those influences in the atmosphere, that play over our nerves like fingers on stringed instruments, and call forth now a sweet, exultant note, and now the saddest wail?
