Cancer, ruled by the Moon and associated with the fourth house, represents cardinal water energy. An evolutionary goal of Cancer is the development of a radically open heart and the utilization of nurturing capacities. Another is the attunement to and the expression of inner feeling states and imagination. Strongly intuitive and very impressionable, Cancer sees the wounded child within everyone. Just as she feels the pain of others, she must learn to accept and honor her own sensitivity and to become emotionally vulnerable with others. She is challenged to develop clan-like bonds with others in which genuine emotional sharing takes place. .

A pitfall of Cancer can occur when she fails to shed her protective Cancerian crab shell and doesn't reveal her own needs or denies her sensitivity. This is a defense mechanism because Cancer takes in pain very deeply and is inwardly very vulnerable, whether she admits it or not. If she is overzealous as a caretaker as a defense against acknowledging her own needs, she becomes "invisible" in terms of her own needs getting seen or met. Another pitfall of Cancer can occur when she feels the need to be needed so much that she tries to become indispensable to those she cares about, and subtly takes emotional hostages by not fostering independence in others.

Security and a sense of home and family are important to Cancer. She can live in the past and want to stay secure and hidden within her home. She could become clingy, dependent, and overly emotional. Cancer, at her finest, is a positively nurturing and comforting force for others. She creates a sense of family and emotional intimacy with those she loves. The genuine sense of family she creates allows a healthful balance between her ability to nurture others and her ability to allow her own sensitivity, vulnerability, and emotional needs to shine through.