Through personification and vivid imagery, the speaker creates a joyous and peaceful representation of the daffodils which soothe his mind in this poem.
The imagery is breathtaking in the most natural sort of way. The daffodils are "golden" as they crowd together around a lake. They embody human qualities—fluttering and dancing—as the wind blows them, and this personification furthers the light and joyous tone.
Metaphorically, the speaker compares these dancing flowers to the number of stars that twinkle throughout the Milky Way, too many to count and impossible to fully appreciate individually. Instead, part of the wonder lies in the fact that there are so many of them together, flooding his visual field.
The speaker uses anthropomorphism, giving the daffodils "heads" that they intentionally toss around as they "dance." And although this dance occurs along the water's edge, the waves themselves a magical visual to behold, the flowers outshine the beauty of the lake.
This scene of "sprightly" daffodils frolicking along the beauty of a wavy lake lightens the speaker's mood. He notes that he cannot help but be happy to witness it, and he considers the scene a great resource to tuck away for future reference.
The poem ends with the speaker's conclusion that this delightful memory is enough to lift even his most "pensive mood" when he recollects the scene. Through various types of figurative language, the description of the daffodils is developed to convey the power of lovely memories.