《吕氏春秋·论·士容论》
覆土过厚，萌芽就钻不出地面；覆土过薄，种子就会遭到闭锢而不能发芽。
厚土则孽不达，薄土则蕃轓而不发。
If the topsoil is too thick, the sprouts will not be able to emerge from the ground; if the topsoil is too thin, the seeds will be blocked and cannot germinate.