The relationship between the Captain Kirk, Science Officer Spock and the Medical Officer McCoy is central to the original Star Trek. Kirk as the key figure in the myth is constantly balancing his decisions based on positions of Spock and McCoy.
Spock, representing the pure thinking part of us, is cold and logical, sometimes appearing inhumane to those disagreeing with his difficult life or death decisions. His position is occasional shown correct.
McCoy, representing the pure feeling part of us, is a true Humanist and Humanitarian setting life above all else.
Kirk mediates between the two men and bi-polar extremes of the psychological drama.
Symbolically, without Kirk present, Mc Coy and Spock argue constantly.
McCoy views the Vulcan’s logic as ruthlessly utilitarian and loses the fact that Spock has saved his life and other lives many times.
Spock, as a half-human Vulcan, has taught himself to reject his mother’s influence and suppress emotion in favor of pure logical thinking of his Vulcan father that represents pure objectivity.
This is the psychodrama of a patriarchal society that is not socialized to accept the mothering side of humanity. Look too at the Greek use of Vulcan as the image of the builder who constructed with metal and was married to Venus. These opposites are put in opposition within Spock. When his human side peeps through it is with humor.
This intensifies the running love-hate working relationship he has with McCoy. McCoy senses that Spock is more human, and more envious of human feeling, than he ever admits.
This too is psycho-myth and the mythmaker is telling us that we should let our feeling side be more exposed.
The Metaphysics of Star Trek by Rev. Len DeRoche