Final answer:
The quote that best connects Twain's first and 1906 speeches is about overcoming fear, indicating he only had stage fright and seasickness once, symbolizing personal growth.
Step-by-step explanation:
The quotation that best describes the connection between Twain's first speech and the speech he gave in 1906 is: "I had stage fright then for the first and last time. I was only seasick once, too." This quote represents both the theme of overcoming fear and the personal development of the speaker. It suggests that just as the speaker was only seasick once, he only experienced stage fright once, indicating a singular event in his life that he overcame, leaving him more confident and capable thereafter. The quote epitomizes how an intense, uncomfortable experience can lead to personal growth and the overcoming of similar challenges in the future.