As role models, the Maha Sangha propagated the Buddha Dhamma in accordance with the Buddha’s profound pedagogy of teaching by self-example. This is exactly how the Supremely Self-enlightened Peerless Teacher, the Buddha, had lived throughout His 45 years-long commitment to practicing and teaching the Sublime Dhamma.
The Buddha demonstrated that teaching by self-example, without question, is the most effective way to guide people. Monks and nuns are to likewise guide lay people to live and breathe the Sublime Buddha Dhamma by promoting the skillful practice of the religion especially by way of their own unblemished character and conduct.