Read the excerpt from Early Victorian Tea Set.

Among the upper classes, tea had been popular since before 1700. It received celebrity endorsement from Charles II’s queen, Catherine of Braganza, and from Queen Anne. It came from China, it was expensive, refreshingly bitter and drunk in tiny cups without milk or sugar. People kept their tea in locked tea caddies, as if it were a drug; for those who could afford it, it often was. In the 1750s Samuel Johnson confessed himself a happy addict:

A hardened and shameless tea drinker, who has for twenty years diluted his meals with only the infusion of this fascinating plant, whose kettle scarcely has time to cool, who with Tea amuses the evening, with Tea solaces the midnights, and with Tea welcomes the morning.

MacGregor’s main purpose in providing the quote is to

The author explains how tea was popular among the upper class. He quotes Samuel Johnson to illustrate its popularity.

Explanation:

The author explains how tea was popular among the upper class. He quotes Samuel Johnson to illustrate its popularity.

taking into account that a theme is the central topic a text treats and can be developed through a story, play, poem etc. the following are themes that can be further developed:  

my best friend jeffrey has many unusual interests. (the story could be about each of the unususal interests)

once a man gives his soul over to evil, he can never go back. (this could be a saying or a proverb)

the three sheepdogs lay around the yard all day. (it could be developed detailing how each of these sheepdogs lay around)

a priest's collar has an unusual effect upon people. (it could be developed detailing the different effect upon people)

innocence is a powerful force in a world full of corruption. (it could be developed detailing how is a world full of corruption)

king lear is a play shakespeare wrote later. (it is just a sentence and doesnt give any idea or topic to be discussed in details.

evil often wears the disguise of innocence. (this could be a saying or a proverb)

- "there are several movements that doris lessing was associated with. first of all, communism. she pursued her communist beliefs and included them in her writing, and was also a member of several communist book clubs. she is also strongly associated with feminism, her fight for equality and women's rights.

doris lessing is the kind of writer who has followers, not just readers. they have been engaged to her chiefly because of her involvement in major problems, such as politics and woman-ism."