过去我们已经知道,外界的物体经过眼球的瞳孔,水漾液,水晶体,玻璃液,而到达网膜上形成一个倒像,但是由于生活经验的改正,便由倒立像成为正立像,因此我们所见到的一切东西是正立的,这个学说是很正确很科学的。只是在教学上很难讲得清楚,因为同学们有一些怀疑,虽然我们想了许多办法,找了许多例子来证明,因为没有使他们亲眼见到,所以效果就不大。后来听 In the past we already know that the objects in the outside world pass through the pupil, the liquid of the eye, the crystal, the liquid glass of the eye and reach the retina to form an inverted image. However, due to the experience of life, the inverted image becomes the positive image. Therefore, Everything I see is upright. This doctrine is very scientific. It is only hard to make it clear in teaching because the students have some doubts. Although we think of many ways and find many examples to prove that they did not make much sense because they were not seen by their own eyes. Listen later