Basic Information
Name: Samuel Irving Rosenman
Nickname: Sam, Roosevelt's Wordsmith
Born: February 13th, 1896
Died: June 24th, 1973
Nationality: U.S.A.
Hometown: San Antonio, Texas
WORK & EDUCATION
Occupation: White House Counsel (Speechwriter)
Education: Columbia University Law School
FAMILY & FRIENDS
Parents: Solomon and Ethel Rosenman
Siblings: N/A
Spouse: N/A
Children: N/A
Friends: Franklin D. Roosevelt, Robert Trout, Harry Butcher
Foes: None
Analysis
While FDR's "First Fireside Chat" might sound conversational and informal to you, it actually went through a whole bunch o' drafts behind the scenes (as did the other fireside chats).
Sam Rosenman was Roosevelt's speechwriter at the White House, and he worked closely with the president to write and speak in a way that would capture the public's attention. "First Fireside Chat" begins with the line "My friends" (1), which was agreed upon by FDR and Rosenman. (Guess they decided against starting out by saying "Dearly beloved…")
In fact, Rosenman encouraged the president to use words that everyone could understand, so that the speech didn't sound too aloof or, well, presidential. The whole point was to sound conversational and friendly.
Here's a fun fact for you: in the fireside chats, about 80% of the words Roosevelt chose to use (with the help of Rosenman) come from the one thousand most commonly used words in English. (Source)
As Rosenman himself said, "[Roosevelt] looked for words that he would use in an informal conversation with one or two of his friends." (Source)
The spirit of the fireside chats included speaking plainly and clearly, appealing to a very wide audience, and not seeming aloof or apart from the people. Rosenman played a big part in helping Roosevelt create this atmosphere through his words.