In Chapter 13, in Roosevelt's inaugural speech, what lesson did he say had been learned and at what cost?

In Roosevelt's fourth inaugural speech, he say that they had learned lessons from the war at a horrible cost. He say that they learned that they cannot live alone in peace. That the United States is dependent upon the well-being of other nations. He also said that it had been learned that Americans must live as men, not as ostriches or dogs in a manager. He added that lasting peace could only be gained by proceeding with confidence and courage that flowed from conviction.