Three short lines capture a single quiet moment: rain dripping from green leaves after a shower. The speaker watches the water fall and sees something far more precious than weather. The rain is "sky's fresh nectar," a sweet drink that feeds the leaves, and then "pure ambrosia," the food of the gods in Greek myth. In just a few words, an ordinary wet garden becomes a kind of feast.
The speaker feels wonder and gratitude. There's no complaint about getting wet or any gloom about grey skies. Instead, the rain is a gift, and the leaves are lucky to receive it. The repeated "drip, drip" slows everything down, so we almost hear each drop landing. The mood is calm, fresh and gently joyful, the feeling of standing still after rain and noticing how clean and alive everything looks. The poem suggests that something simple, if we pay attention, can feel almost sacred.