Spiritual knowledge is also a science. It is not sentiment; it is science. Now, if you like, you can make research work whether this is fact. Just like this cow dung. You may think that, "This is contradiction. In one place it is said that stool of an animal is impure, now here it is again said that cow dung is pure. It is contradiction." So if you like, you can make analysis. But you accept the Vedic injunction as it is—you save so much time, that's all, and immediately become advanced.
Therefore the Veda says that in order to learn that spiritual science, you must approach a person, tad-vijñānārthaṁ sa gurum eva (MU 1.2.12), who is guru. Guru means spiritual master. And who is spiritual master? Who abides by the disciplic succession. He does not change. He does not interpret. He presents things as they are. Just like we are doing. We are presenting Kṛṣṇa as the Supreme Personality of Godhead. Kṛṣṇa says that . . . for spiritual realization, He says, man-manā bhava mad-bhakto mad-yājī māṁ namaskuru (BG 18.65). Kṛṣṇa says that, "Always think of Me." Man-manā. Man-manā means "about Me." Man-manā bhava mad-bhaktaḥ: "You just become My devotee."