Men build too many walls and not enough bridges.

This became widely attributed to Isaac Newton after Dominique Pire ascribed it to "the words of Newton" in his Nobel Lecture, 11 December 1958. Pire refers not to Isaac, but to Joseph Fort Newton, who is widely reported to have said "People are lonely because they build walls instead of bridges." This appears to be paraphrased from a longer passage found in his essays and addresses, The One Great Church: Adventures of Faith (1948), pp. 51–52: "Why are so many people shy, lonely, shut up within themselves, unequal to their tasks, unable to be happy? Because they are inhabited by fear, like the man in the Parable of the Talents, erecting walls around themselves instead of building bridges into the lives of others; shutting out life."