Where do crows enjoy? In a filthy place. But white swans take pleasure in nice clear waters surrounded by gardens. So even among animals there are natural divisions. The crows will not go to the swans, and the swans will not go to the crows. Similarly, in human society there are men who are like crows and men who are like swans. The swanlike men will come to centers of Krsna consciousness, where everything is clear, where there is good philosophy, good transcendental food, good education, good intelligence — everything good — whereas crowlike men will go to clubs, parties, naked dance shows, and so many other such things.

So the Krsna consciousness movement is meant for swanlike men, not for men who are like crows. But we can convert the crows into swans. That is our philosophy. Those who were crows are now swimming like swans. That is the benefit of Krsna consciousness.

The material world is the world where swans have become crows. In the material world the living entity is encaged in a material body, and he tries to gratify his senses in one body after another. But the reestablishment of dharma will gradually turn crows into swans. For example, a man may be illiterate and uncultured, but he can be converted into an educated, cultured man by training.

(Srila Prabhupada — TQK 16: Returning to Our Natural Consciousness)