The speaker starts with a small burst of delight: look, a cat asleep in front of the moon! Almost at once they correct themselves. It's only a cloud. But the correction doesn't spoil the fun. Instead the speaker keeps playing, asking whether you can also see grey kittens on the moon's surface. Those dark patches become kittens, and then something stranger: dead volcanos that give milk to "Jacob's angels."
The poem moves from ordinary looking to pure imagination, each step a little more surprising than the last. The speaker feels playful and wonder-struck, like someone lying on the grass finding shapes in the sky and inviting a friend to join in. The mood is light, dreamy and slightly mischievous. The reference to Jacob's angels seems to nod to the biblical story of a ladder with angels, though the poem doesn't explain it, which adds a touch of mystery. The poem seems to suggest that seeing something "wrongly" can be a pleasure in itself.