"Fern Hill" by Dylan Thomas is a nostalgic and reflective poem that explores several themes, often associated with childhood, memory, time, and the fleeting nature of life. Here are some of the key themes in the poem:

• Childhood and Innocence: In Fern Hill, Dylan Thomas beautifully remembers his happy childhood. The poet describes a time when he was free, innocent, and full of joy. He played under the apple trees. He ran through the fields. He felt at one with nature. Everything around him, the sunlight, the grass, the animals, seemed alive and friendly. His world was simple and perfect. His world was untouched by sadness or worry. This period of childhood is shown as a golden time. This time is full of purity and wonder. Yet, the poet also hints that such happiness cannot last forever. Childhood slowly fades away as time moves forward. This leaves only memories behind. 
• Time and Change: The theme of time runs throughout the poem. At the beginning, time is gentle and kind. It lets the young boy enjoy life freely. But as the poem continues, time becomes powerful and cruel. It takes away the beauty and innocence of youth. The poet realizes that time never stops. It keeps moving. It changes everything. The final lines, “Time held me green and dying, / Though I sang in my chains like the sea”, show that time controls all life. Yet, even in this chain of time, the poet continues to sing, to celebrate life. This theme reminds us that joy and loss are both part of the same journey. 
• Nature and Harmony: Nature plays a central role in Fern Hill. It is not just the setting, but a living presence. It fills the poet’s childhood with music, light, and energy. The fields, rivers, stars, and animals become his friends and companions. The poet feels a deep harmony with the natural world as if he and nature are one. Through nature, he experiences freedom and spiritual peace. But as he grows older, this connection fades, just like his innocence. Still, nature remains a symbol of eternal life and beauty. It teaches that even when youth and joy pass away, the rhythm of life continues forever.