Sri Chinmoy: In a particular class in school we have perhaps forty students studying the same subjects together under one teacher. Similarly, in the spiritual world, some souls want to move together and make progress together. It is much like a relay race where four persons are required.
When the soul incarnates in a human body, it is endowed with human propensities and it gets the opportunity to mix with other souls. In the inner world as well as in the outer world, souls choose according to their preference. Some souls want only light: they do not care for power, they do not care for joy, they do not care for peace. They want only light, light, light. If a soul cares for light, then naturally it will be pulled and attracted by another soul which cares only for light. The group souls unite themselves with light or power or peace or some other predominating divine quality. If light is connecting a particular group of souls, then that group will have more light than power. If it is power that unites them, then they will have more power and less light. These souls will have a natural inner connecting link among them.