“You are what your deep, driving desire is. As your desire is, so is your will. As your will is, so is your deed. As your deed is, so is your destiny.”—Brihadaranyaka Upanishad (IV.4.5)
Let us classify the castes (simplistic?) according to this principle:
If your deep, driving desire is for:
Knowledge and wisdom — then, you are a Brahmin
Power, authority, leadership — then, you are a Kshatriya
Money, resources — then, you are a Vaishya
Enjoyment — then, you are a Shudra
Someone commented: If so, a vast majority of the people in the world would love to be Shudras, isn’t it?
I replied: True, but without the acquisition of the other goods that the other higher castes are seeking, that enjoyment is precarious, hard to obtain, and cannot be sustained…and that does NOT mean the other castes are NOT enjoying…the Brahmin gets enjoyment from knowledge and wisdom, and that very knowledge and wisdom can bring in its train power, leadership, authority, money, resources, and enjoyment…but NOT necessarily in the measure in which the other castes are seeking them, but the Brahmin would have understood the significance of contentment, and therefore even if he has in less measure the goods that other castes have, he will still be as happy. But, every caste will have access to the goods of all the castes lower to it but very rarely access to the goods of the castes higher to it, if I can put it simplistically.
Know Thyself 