Within the Set, Mary Macgregor is employed as a foil to the others. Where they are graceful, artistic and intelligent, Mary is '...a silent lump, a nobody whom everybody could blame.' (p8) Nevertheless, Mary is an integral member. During a walk, Sandy reacts against Set and Brodie thinking by wanting to be nice to Mary:

The sound of Miss Brodie's presence, just when it was on the tip of Sandy's tongue to be nice to Mary Macgregor, arrested the urge ... She perceived herself, the absent Jenny, the ever-blamed Mary, Rose, Eunice and Monica, all in a frightening little moment, in unified compliance to the destiny of Miss Brodie, as if God had willed them to birth for that purpose. (p30)

Sandy's rightly suspects that Miss Brodie wants Rose to sleep with Teddy Lloyd. Brodie herself had earlier had an affair with Lloyd, and now wants Rose to become his lover in her place. It is when Sandy fully realises this that she takes action against Miss Brodie. Teddy Lloyd has no sexual interest in Rose however, and in a ironical twist of fate, it is Sandy who becomes his lover. Spark does not specify whether or not this is an intentional act of rebellion, but Sandy fully appreciates how this contradicts the wishes of her erstwhile mentor.

Spark's narrative development, portrays in Sandy, a character whose growing moral and intellectual awareness obliges her to react against Miss Brodie. At the end of the novel, this becomes a physical action, by which she means to put a stop to the Brodie influence on people. Brodie actively encourages Joyce Emily, a new girl at Marcia Blaine, to go to Spain to fight for the right wing Franco in the Spanish Civil War, where she is killed. Sandy finds this morally reprehensible, and reports her former teacher to the authorities. Thus the influence of Miss Brodie is stopped.

This decisive moment is the keystone in the decline of Miss Brodie. From this moment on, Spark depicts in Sandy, a character who begins to react against her mentor, firstly in thought, and ultimately in action. This action results in Sandy 'betraying' Miss Brodie to the school authorities, which prompts her dismissal from Marcia Blaine.

Brodie confides on all manner of subjects to her Set, including her love life, religion, art and politics.

Some common words found in the essay are:
Miss Brodie, Miss Brodie's, Mary Spark, Teddy Lloyd, Sandy Set, Marcia Blaine, Mary Macgregor, Mathematics Sandy's, Sandy Stranger, miss brodie, Jean Brodie', miss brodie's, marcia blaine, nice mary, teddy lloyd, miss brodie's influence, sandy's growing, sandy character, brodie's influence, mary macgregor, influence miss, 'the prime miss, miss jean brodie', prime miss jean, influence miss brodie,
Approximate Word count = 1054
Approximate Pages = 4 (250 words per page double spaced)