The symbolism in "I Wandered Lonely as a Cloud" reinforces the importance of nature by demonstrating its ability to bring great joy.
The cloud becomes a symbol of loneliness, as the title indicates. Clouds are able to observe the earth's beauty from a distance but remain disconnected from any sense of earthly intimacy. As the poem begins, the speaker feels similarly disconnected and isolated, and his heart aches with loneliness.
In contrast, the speaker's mood is greatly lifted when he spies the daffodils, which symbolize joy. Their color is "golden," which connotes great value and splendor. They dance freely in the breeze, mimicking the festive actions of humans as they flutter. Daffodils are one of the first signs of spring's emergence, so they also symbolize new life; this symbolism is central to the speaker's thoughts in the final stanza. He contemplates how his memory of the daffodils has the ability to transform any "pensive mood" which he suffers in "solitude."
The waves also "dance" in this picturesque scene. As part of the Earth's natural beauty, they symbolize freedom and serenity. Although the speaker appreciates the beauty of the waves, he finds that they pale in comparison to the simple beauty of the daffodils.