A child climbs a playground ladder, counting each rung, and then slides back down to where he started. That simple scene carries a bigger idea. The counting runs up, "one, two, three," then reverses as the ground falls away, "three, two, one." As he rises, the poem calls the sky and the Future "bright and bold" and the ground and the Past "dull and dead." Climbing feels like leaving something behind and reaching toward something better.
The slide itself is quick and joyful, "a roly, jolly ride," with wind on the face. But the speed also rushes the ground back up, and the last line lands with a "thud." He ends "where all it began." The mood moves from eager excitement to cheerful thrill and then to a small, abrupt jolt. The poem suggests, gently, that effort and ambition can end in a circle, though the child's delight in the ride may be the point.