(Kadamba Kanana Swami, 06 September 2016, Cape Town, South Africa, Srimad Bhagavatam 1.9.26)
Intelligence is found in the two upper classes of men – in the brahminical class and the kshatriya class. The intelligence of a vaishya is of a different nature because the intelligence of a vaishya is less selfless. The brahmana and kshatriya sacrifice their self-interest for the sake of dharma so their lives are dedicated to a higher duty. Whereas the vaishya is also intelligent but his intelligence is focused on profit and on personal gain. So when the choice comes between following a principle and making a profit, the vaishya then puts the principle on the shelf, makes the profit and the next day re-adopts the principle, you know what I mean. But the vaishyas get purified by dharma, by generosity, by giving and in this way, they fulfil their duty.
For a sudra, principles are a difficult thing to deal with because, “I don’t feel it!” so then how can they do it! The sudra does what he ‘feels’ is right. Therefore kalau sudra sambhava (Skanda Purana), in this age everyone is classified as sudra because we do what we feel.