Wiglaf is presented as Beowulf's savior and helper. He is there to mentor Beowulf and is an important character in this excerpt.
I think that the central idea conveyed in the above excerpt is that the United States is willing to extend help to nations that are under communism. They are willing to extend help through financial aid and economic stability to ensure that the people under the beleaguered nations can also enjoy the freedom that citizens of the United States enjoy under a democratic government. However, the citizens of the United States must also be in agreement to the proposal of extending help to other nations.
Truman uses Logos and Pathos to persuade his audience to his way of thinking.
Logos refers to logic. Pathos refers to an appeal to emotions.
He uses the words "I believe..." to infer how passionate he is about his proposals. He also gives logical scenarios that supports his beliefs.
A FOX one day fell into a deep well and could find no means of escape. A Goat, overcome with thirst, came to the same well, and seeing the Fox, inquired if the water was good. Concealing his sad plight under a merry guise, the Fox indulged in a lavish praise of the water, saying it was excellent beyond measure, and encouraging him to descend. The Goat, mindful only of his thirst, thoughtlessly jumped down, but just as he drank, the Fox informed him of the difficulty they were both in and suggested a scheme for their common escape. "If," said he, "you will place your forefeet upon the wall and bend your head, I will run up your back and escape, and will help you out afterward." The Goat readily assented and the Fox leaped upon his back. Steadying himself with the Goat's horns, he safely reached the mouth of the well and made off as fast as he could. When the Goat upbraided him for breaking his promise, he turned around and cried out, "You foolish old fellow! If you had as many brains in your head as you have hairs in your beard, you would never have gone down before you had inspected the way up, nor have exposed yourself to dangers from which you had no means of escape."
What is the moral of the story? Think things through before taking action. Don't be impulsive.
Basically, the theme is think before you leap.
If you look at a dictionary to substantiate is to support an opinion or claim with proof or evidence. So a Substantiated opinion is an opinion that is backed up with proof.
Hope this helps :)