They may be used repeatedly for fresh work,until the time,sometimes very distant,at which they are worn out,while the work already done by them may subsist unimpaired,and when it perishes,does so by its own laws,or by casualties of its own.

• 工具，可反复用来制作新的物品，直到用坏为止，有时用坏要花很长时间，而用工具制作的物品则会继续存在，制作的物品只会因其自身的规律或其自身的事故而毁坏。