“All living entities are rotating throughout the universe, going sometimes up to the higher planetary systems and sometimes down to the lower planets. This is the material disease, which is known as pravritti-marga. When one becomes intelligent he takes to nivritti-marga, the path of liberation, and thus instead of rotating within this material world, he returns home, back to Godhead. This is necessary.” (Shrila Prabhupada, Shrimad Bhagavatam, 6.1.2 Purport)