《吕氏春秋·论·士容论》
这是农事的大害。所以，田畦应该又宽又平，垄沟应该又小又深。这样，庄稼下得水分，上得阳光，才能苗全苗壮。
故亩欲广以平，甽欲小以深，下得阴，上得阳，然后咸生。
This is a major hazard in farming. Therefore, the field should be wide and flat, and the ridges and furrows should be narrow and deep. This way, the crops will receive moisture from below and sunlight from above, and they will be able to grow vigorously.