I found a bit more on diffidence in Confucius:
"The Master said, 'I am thinking of giving up speaking.' Tzu-kung said, 'If you did not speak, what would there be for us, your disciples, to transmit?' The Master said, 'What does Heaven ever say? Yet there are the four seasons going round and there are the hundred things coming into being. What does Heaven ever say?'"
-Confucius, The Analects, XVII: 19.