A method of solution is perfect if we can foresee from the start, and even prove, that following that method we shall attain our aim.
如果你无法飞翔,那就奔跑;如果你无法奔跑,那就快走;如果你无法快走,那就爬行。但无论如何,你必须继续前进。
凡是圣人制造的这些东西,无一不是有益于实用才去做的,所以使用财物不浪费,民众能够不劳苦,他兴起的利益太多了。 
Perception is an active process where the brain constructs meaning from sensory input.