In the tree of the material body, the individual soul and the Supreme Soul, or Supersoul, are sitting like two friendly birds. The first bird (the individual soul) is eating the tree's fruits, which are happiness and distress. The second bird (the Supersoul) is simply watching. Although these two birds are friends, and although they are of the same spiritual quality, the Supersoul is the master and the individual soul the servant. But the individual soul has forgotten this relationship, and thus he must transmigrate from one tree to another, or from one body to another. The individual soul is struggling very hard on the trees of innumerable material bodies, but as soon as he agrees to accept the guidance of the Supersoul, the supreme spiritual master, he immediatly becomes free from all lamentations.
Reference~ Shimad Bhagavatam, First Canto by His Divine Grace A.C. Bhaktivedanta Swami Prabhupada