It is said that a Brahmana's duty consists in studying the Vedas and seeking the behoof of humanity that a Kshatriyas duty consists in protecting men and that a Vaishyas promoting their material prosperity.
स्वाध्यायनिरता विप्रास्तथा स्वस्त्ययने नृणाम्। रक्षणे क्षत्रियं प्राहुर्वैश्यं पृष्ट्यर्थमेव च॥