You take a nine-month-old and for Piaget a nine-month-old is just starting to make sense of objects and their permanence.

你找到一个九个月大的婴儿,在皮亚杰看来,九个月大的婴儿才刚刚发展出,客体以及客体永存性的概念

耶鲁公开课 - 心理学导论课程节选

I think the reason that it grew slowly was that insurance is a very sophisticated concept.

我认为之所以导致缓慢发展在于,保险学是一个非常复杂的概念

耶鲁公开课 - 金融市场课程节选

And it's through this stage that a child gradually comes to acquire object permanence.

在这一阶段,儿童逐渐发展起,客体永存性的概念

耶鲁公开课 - 心理学导论课程节选