Ambassador Sarek crying
a particular piece of the music has moved him to tears
is the title of an episode from the third season of Star Trek: The Next Generation. The episode features Sarek, the famous Vulcan Ambassador (first seen in the classic Star Trek episode Journey to Babel).
Sarek has come as part of a diplomatic mission to establish relations between the United Federation of Planets and the Legarans, his last mission before retiring.
Sarek quickly retires to his room, and one of Sarek’s aides explains to Captain Picard that Sarek tires easily, because of his advanced age, and so requests the official welcoming ceremonies be dispensed with.
Deciding to continue with a classical concert that had been planned, Picard extends an invitation to Sarek’s wife, Perrin. When Picard leaves the ambassadorial quarters, Perrin enters Sarek’s room to find the Vulcan annoyed by an inability to meditate. His annoyance is quite out of character for Sarek, and indeed any Vulcan.
That evening, Sarek, his wife and his aides attend a Mozart concert. Picard is shocked when he notices Ambassador Sarek crying – a particular piece of the music has moved him to tears (incidentally, the piece played was actually the Andante in D-minor movement of Brahms‘ “Sextet #1 in B-Flat Major”, though only four characters are shown performing the piece).
The music played by the string quartet is a part of the String Quartet No.19 in C-Minor by Wolfgang Amadeus Mozart. The second part in that scene fades into the 2nd movement of the “String Sextet No.1” by Johannes Brahms
The point at which he cried is at the beginning of this Brahms piece below (listen)