LitCharts assigns a color and icon to each theme in The History of Tom Jones, a Foundling, which you can use to track the themes throughout the work.
Virtue vs. Vice
Marriage, Romance, and Economics
Appearance vs. Reality
Coming of Age
Storytelling, Literature, and Structure
Summary
Analysis
Meanwhile, Sophia has heard the whole story about Molly. Her maid, Mrs. Honour, wants to gossip with her about Molly, but Sophia cuts her off, saying she has no interest in what Tom and Molly do in their private lives. Secretly, Sophia had been holding on to a passion for Tom, never realizing what the consequences of this passion might be. She wants to forget him, but just like with a physical disease, the next time she sees Tom, she has a relapse.
The comparison of Sophia’s love for Tom to a physical disease suggests that it is to some extent involuntary. While the novel looks at the way people are motivated to seek marriage based on rational reasons like trying to obtain inheritances or property, it also looks at how there are more mysterious and less well understood components to romance.