CC Madhya 24.93
ataeva hari bhaje buddhimān jana
“With the exception of devotional service, all the methods of self-realization are like the nipples on the neck of a goat. Therefore an intelligent person adopts only devotional service, giving up all other processes of self-realization.
Without devotional service, other methods for self-realization and spiritual life are useless. Other methods cannot produce good results at any time, and therefore they are compared to the nipples on the neck of a goat. These nipples cannot produce milk, although it may appear that they can. An unintelligent person cannot understand that only devotional service can elevate one to the transcendental position.