What is the purpose in beginning this speech with a reference to Abraham Lincoln?

Understood McCarthy's purpose and use of rhetorical devices

Explanation: Hope this helped!

quite an interesting way to teach topic sentences, because the answer to this question is the best definition of a topic sentence that one can present, it is as if answering the questions taught you how to do it, this is some real teaching, it is terribly well-done.

the topic sentence in this paragraph is:

topic sentences writers stay on track and keep a paragraph from becoming an aimless collection of sentences about an idea.

which incidentally tells you what a topic sentence should be.

the anwser is went creeping down the river again, across the wide lonely marshes to the sea.

i longed to go with them out into the world to seek my fortune in foreign lands—africa, india, china and peru!

and, dreaming of the lands i had never seen, i'd sit on there, watching till they were out of sight.