Captain's log

In a parallel universe, the captain's log was a form of record-keeping that was used by starship captains of the Starfleet of the United Federation of Planets. Such a captain's log was kept by James T. Kirk, captain of the USS Enterprise. (COMIC: Assimilation²)

Destrii cited "the bit where Sulu has to do the captain's log" as a particularly memorable moment of the Star Trek episode Spock's Brain, to the point of quoting back a portion of the log, in unison with Izzy Sinclair: "Captain Kirk's hunch that Spock's brain is on this planet appears to be correct!" (COMIC: Ophidius)

Behind the scenes
The actually is a direct quote from the episode and it was entered by Sulu. Technically, however, it was a ship's log, rather than a captain's log.