What is the theme of Candida?

"Candida" is a play by George Bernard Shaw, written and published at the end of the 19th century. To glean the central theme of the play, one need look no farther than the title. The play is titled after one of the main characters, making it clear readers and viewers should focus on Candida and understand the outcomes of the play through her eyes above all else. Candida is caught between the conventional yet strong bond of marriage to Morrell, and the allure of a high-minded, freedom-seeking poet named Marchbanks.
The theme of the play is that women should have the right to navigate the line between security and freedom, domesticity and boundless imagination, for themselves. Candida is a strong female character, and indeed "candid" or frank in her words and actions. Ultimately, she decides not to pursue the life which is more viscerally compelling, but the man who needs her the most, her husband Morrell. Her decision is final by the end of the play when she says "I give myself to the weaker of the two."
At the end of the Victorian era, society was deeply questioning the role and scope of women's rights, what women were capable of, and how much agency they should and could have in making their own life choices. Candida stands at the center of two poles, her husband and her lover, and conscientiously chooses one not out of fear or vanity, but her own moral compass. Even though she chooses the more conventional life, it is unconventional in that she is a woman choosing her own path in life and not merely one set out for her. In this way, the theme of the play is that all people have the right to choose a life of wanton freedom or dedicated domesticity—and the outcome is not nearly as important as the right to choose itself.