Mencius - Book 3, Part 1, Chapter 4C

Mencius resumed, 'Then, is it the government of the kingdom which alone can be carried on along with the practice of husbandry? Great men have their proper business, and little men have their proper business. Moreover, in the case of any single individual, whatever articles he can require are ready to his hand, being produced by the various handi-craftsmen: if he must first make them for his own use, this way of doing would keep all the people running about upon the roads. Hence, there is the saying, "Some labor with their minds, and some labor with their strength. Those who labor with their minds govern others; those who labor with their strength are governed by others. Those who are governed by others support them; those who govern others are supported by them." This is a principle universally recognized.

'In the time of Yâo, when the world had not yet been perfectly reduced to order, the vast waters, flowing out of their channels, made a universal inundation. Vegetation was luxuriant, and birds and beasts swarmed. The various kinds of grain could not be grown. The birds and beasts pressed upon men. The paths marked by the feet of beasts and prints of birds crossed one another throughout the Middle Kingdom.

'To Yâo alone this caused anxious sorrow. He raised Shun to office, and measures to regulate the disorder were set forth. Shun committed to Yî the direction of the fire to be employed, and Yî set fire to, and consumed, the forests and vegetation on the mountains and in the marshes, so that the birds and beasts fled away to hide themselves. Yü separated the nine streams, cleared the courses of the Tsî and T'â, and led them all to the sea. He opened a vent also for the Zû and Han, and regulated the course of the Hwâ'i and Sze, so that they all flowed into the Chiang.

'When this was done, it became possible for the people of the Middle Kingdom to cultivate the ground and get food for themselves. During that time, Yü was eight years away from his home, and though he thrice passed the door of it, he did not enter. Although he had wished to cultivate the ground, could he have done so?'
~ James Legge translation via nothingistic.org ~

Go here to read the introductory post to this serialized version of the Works of Mencius.