The paragraph is followed by an incomplete phrase or sentence which summarizes the main idea of the paragraph. Choose the missing words of the phrase or sentence.

Tears have a more complex chemical composition than was imagined and they might act as one of the body's waste disposal system. Evidence from tear research may warrant a drastic change in our thinking about crying. Although there is such a thing as people weeping to excess, crying in response to various emotions is a natural physical process that we should not be ashamed of.
It is not a shame to let the tears （）