"In the material world field, we love somebody for getting something in return. That is not love, pure love. Pure love is different. Pure love, as it is described by Lord Caitanya in the..., in His mood of Rādhārāṇī unto Kṛṣṇa: āśliṣya vā pāda-ratāṁ pinaṣṭu māṁ marma-hatāṁ karotu vā (Śikṣāṣṭaka 8). This is love, Rādhārāṇī's, that 'You either embrace me or trample me down under Your feet, neglect me, or make me brokenhearted, not being present at any time throughout my life, life after life, it does not matter. Still I love You, unconditionally.' Mat-prāṇa-nāthas tu sa eva nāparaḥ. That is real love. And that love is existing in everyone's heart."
(Srila Prabhupada Lecture, Vrindavan, October 24, 1972)