Let a man meditate on the fivefold Sâman as the five worlds. The hinkâra is the earth, the prastâva the fire, the udgîtha the sky, the pratihâra the sun, the nidhana heaven; so in an ascending line.

In plain words: A person should meditate on the five parts of the sacred chant as five worlds, going upward. The parts match the earth, fire, the sky, the sun and heaven.