Some historical background on the Senate's Rule 19 (which was used to shut up Elizabeth Warren the other day).

From Robert A. Caro,  "Master of the Senate: The Years of Lyndon Johnson III" (pages 92-93):

Courtesy and courtliness were characteristics of the southern aristocracy— and of the Senate, where these traits were not only esteemed but were reinforced by the body’s rules. The rules imposed a verbal impersonality on debate to ensure civility and formality. All remarks made on the floor were required to be addressed not directly to another senator but to “Mr. President” (the presiding officer at the time)— a device that functioned as a psychological barrier between antagonists. Senators speaking on the floor were also required to refer to each other only by title, a device which placed the emphasis on the office rather than the individual (“If I may venture to offer a reply to the distinguished senior Senator from North Dakota”) and was therefore, as a Senate historian notes, “a safeguard against asperities in debate and personalities of all kinds.”
Referring to another senator by name— or by any form of the second person— was forbidden. “There is but one ‘You’ in the Chamber, and that is the Presiding Officer,” Senator George Hoar had said in 1909. “ ‘You’ can never under any circumstances be applied to an individual senator.” During the 1940s, as a Senate observer wrote, addressing a fellow senator in the second person was still “almost an unforgivable sin. It must always be in the third person.” Using exaggeration to make his point, Alben Barkley of Kentucky advised a freshman, “If you think a colleague is stupid, refer to him as ‘the able, learned and distinguished senator,’ but if you know he is stupid, refer to him as ‘the very able, learned and distinguished senator.” The Senate rule— Rule 19— against “asperities” applied not only to individuals (“No Senator in debate shall directly or indirectly, by any form of words, impute to another Senator or to other Senators any conduct or motive unworthy or unbecoming a Senator”) but to states (“No Senator in debate shall refer offensively to any State of the Union”). It was out of order not only for a senator to attack a colleague, but even to read on the floor an attack by someone else— a newspaper article or letter, for example; “when such matter by inadvertence has been read, by direction of the Senate, it has been expunged from the record,” says the Senate historian. And should a senator violate that edict, not only the senator attacked but any other senator, or the presiding officer, could call him to order, and “when a Senator shall be called to order” under Rule 19, “he shall sit down”— at once, without another word—“ and not proceed without leave of the Senate,” leave which could only be granted by formal motion. And, says another historian, “To be called to order under Rule 19 was considered a disgrace then [during the 1940s and ’50s]. Your colleagues wouldn’t meet your eyes. You were in disgrace.” The decorum that characterized the floor of the United States Senate at mid-century was difficult even to imagine at the century’s end. So thoroughly had southern influence brought to the Senate floor the flavor— the graciousness, the formality, the civility (right down to a gift for “gracefully waving away mere political differences with an opponent”)— of the Southland that, in the words of Russell Baker, writing in 1961, the Senate’s manner was “as elaborately courteous as a Savannah lawyer’s.”