In the higher planetary systems, there are not only different types of human beings, but also animals like lions and elephants. There are trees, and the land is made of emeralds. Such is the creation of the Supreme Personality of Godhead. Srila Bhaktivinoda Thakura has sung in this regard, kesava! tuya jagata vicitra: My Lord Kesava, Your creation is colorful and full of varieties. Geologists, botanists and other so-called scientists speculate about other planetary systems, but being unable to estimate the varieties on other planets, they falsely imagine that all planets but this one are vacant, uninhabited, and full of dust. Although they cannot even estimate the varieties existing throughout the universe, they are very proud of their knowledge, and they are accepted as learned by persons of a similar caliber. As described in Srimad-Bhagavatam (2.3.19), sva-vid-varahostra-kharaih samstutah purusah pasuh: materialistic leaders are praised by dogs, hogs, camels and asses, and they themselves are also big animals. One should not be satisfied with the knowledge imparted by a big animal. Rather, one must take knowledge from a perfect person like Sukadeva Gosvami. Mahajano yena gatah sa panthah: our duty is to follow the instructions of the mahajanas. There are twelve mahajanas, and Sukadeva Gosvami is one of them.