For crossing a canal a small raft will be enough. One or two can go in it. To cross a river, a boat is needed. It can accommodate ten to fifteen passengers. But to cross an ocean, a huge ship or ocean-liner is required. It can carry hundreds in it. The world is like a big ocean. To help humanity to cross this ocean an Avatar or World Teacher (ocean-liner) is needed. The ordinary gurus are like the rafts and boats that can benefit only a few persons. An Avatar gives rise to several gurus. (NNSG Vol.5, p. 13)