in the republic when he talks about the 3 classes of men it sounds very like the 3 vedic twice born varnas.
the one of the teacher, leader, worker
as for the couler thing i rely do not knww but it is tru the very lowest casts are very dark skinned. but some is also the same a for a few high cast people.
Also an other thing is the cast system is severely misunderstood along with many other aspects of Hinduism I have only come into conciseness of this after looking deep into the religion and searching for the truth.
I have found out that even a shudra (lowest cast) could do the same job as a Brahman (highest cast) and have the exact same respect. But in order for this to happen the sudra would have to show the qualities of a Brahman.
One that is Brahmana, when he becomes wicked in conduct and observes no distinction in respect of food, falls away from the status of a Brahmanhood and becomes a Sudra.
Even a Sudra that has purified his soul by pure deeds and that has subjugated all his senses, deserves to be waited upon and served with reverence as a Brahmana.. This has been said by the Self-born Brahman (supream god in Hinduism everything is him, everything comes from him and everything goes back to him) Himself. When a pious nature and pious deeds are noticeable in even a Sudra, he should be held superior to a person of the three regenerate classes. Neither birth, nor the purificatory rites, nor learning, nor offspring, can be regarded as grounds for conferring upon one the regenerate status. Verily conduct is the only ground
so although someone might have been born a certain cast through their efforts it was possible for them to move up. This was the idea of the vidic texts but later this system got rigged and locked it became very difficult for any mobility. The problem in my view is more of a social one rather then religious one.
As I read more I am beginning to find out that Hinduisms biggest enemies are Hindus them selves.
Regards
Mer