The following are three types of knowledge Isabel gains in the course of the novel.
Knowledge of the deceit of others. The duplicity of human beings is one specific aspect of knowledge that Isabel grasps. Throughout her narrative, Isabel experiences the multi-dimensional aspect of interpersonal knowledge. Isabel gains the knowledge that human beings are complex creatures and capable of great deceit and masquerade. For example, how Osmond seems prior to knowledge is nowhere near how he is during marriage. James suggests that "deliberately, almost malignantly, [Osmond] had put out the lights, one by one" in Isabel's innocence. In her marriage to Osmond, Isabel sadly learns this. Isabel experiences the same type of revelation in her dealings with Madame Merle. Isabel's initial impression of Madame Merle was one of respect. Madame Merle's "polished manners and many accomplishments" helped to "inspire" a sense of admiration within Isabel. Over time, this becomes supplanted with a more realistic and sober view of Madame Merle, one that the complex character reveals herself when she says, ""I don't pretend to know what people are for ... I only know what I can do with them." These interactions help to fill Isabel with the knowledge that people are not what they seem to be. Isabel realizes the complexity intrinsic to human beings, capable of possessing different layers to their identity. Isabel gains this aspect of knowledge as a result of her interactions with others.
Knowledge of the corruption of money. Another aspect of knowledge that Isabel gains is that money can be a source of corrosion. Isabel's problems being to settle in once she inherits the large amount of money. While "money gives freedom," Isabel understands that many of her choices become more complex and more intricate as a result of money. While money does enhance Isabel's freedom, she also learns that it attracts individuals and creates a sense of coveting within human beings. Initially, Isabel is "eager to see the world and broaden her experience." Interestingly enough, Isabel finds that as a result of money and her marriage to Osmond, both realities become more limited. Money is the means by which Isabel's sense of innocence and zeal with which she approached the world was taken. This becomes another aspect of knowledge that becomes clear to Isabel.
Knowledge of personal freedom. Finally, Isabel recognizes different aspects of knowledge about her own freedom. Isabel initially seems to acknowledge her freedom in a simplistic and monistic light. As a "free and keen girl," she believes that her own sense of authenticity and passion with which she appropriates the world will be reciprocated. After her interactions with people such as Osmond and Madame Merle and the truths accompanied within them, Isabel recognizes that freedom is complex. It is ambiguous and unclear, filled with different elements that cannot be fully anticipated. This knowledge becomes clear in the ending in which Isabel takes action:
Here . . . she paused. She looked all about her; she listened a little; then she put her hand on the latch. She had not known where to turn; but she knew now. There was a very straight path.
What exactly that path might be is not clear. While it is not clear what Isabel will do, there is a certainty in her need to act. Isabel gains the knowledge that while freedom is complex and intricate, the will to act upon it must be decisive and consist of a resolve that follows "a very straight path." Isabel's characterization is one where this aspect of knowledge becomes evident to her as a result of her experiences.