'How can it be so clear? Because fresh water flows in from its source' are the best-known lines of 'Thoughts on Reading'.
Tips
culture
The first of the two poems by 朱熹 opens 半亩方塘一鉴开，天光云影共徘徊 'a half-acre square pond opens like a mirror, where skylight and cloud shadow drift together'. The pond is the mind and its spring is reading, which gave the idiom 源头活水.
mistakes
那 in 问渠那得清如许 is an old way of writing 哪 'how', so it is read nǎ, not nà.
