In the material world we are simply chewing the chewed, throwing it away, picking it up and then chewing it again. Spiritual variety is not like this. Spiritual variety is anandambudhi-vardhanam: it is constantly increasing. It is even greater than the ocean because the ocean does not increase. The shores of the ocean are set; they have certain limits. However, the ocean of bliss is constantly increasing. The more we enter into that spiritual bliss, the more we become joyful. The young people in the Hare Krishna movement chant the Hare Krishna mantra all the time. If this mantra were material, how long would they chant it? It is not possible to chant a material name for very long because the chanting would become hackneyed and very tiresome. No one could be satisfied simply by chanting Hare Krishna unless Hare Krishna itself were spiritual. We may chant, “Mr. John, Mr. John, Mr. John,” but after an hour we will be fed up. However, the more we become spiritually advanced, the more bliss we will derive from chanting Hare Krishna.
Source: A.C. Bhaktivedanta Swami Prabhupada (2007 edition), “Teachings of Lord Kapila, The Son of Devahuti”, Page 179