Solution

We feel happy by coming into contact with things of beauty. They make a lasting impression on us. Keats makes it clear at the outset. A thing of beauty is a joy forever. It is a constant source of joy and pleasure. Its beauty never declines or diminishes. Its loveliness goes on increasing every moment. Its value remains undiminished. It never passes into nothingness. It removes the pall of sadness that covers our dark spirits.