Knowing one's emotions. Self-awareness — recognizing a feeling as it happens — is the keystone of emotional intelligence. . . . The ability to monitor feelings from moment to moment is crucial to psychological insight and self-understanding. An inability to notice our true feelings leaves us at their mercy. People with greater certainty about their feelings are better pilots of their lives, having a surer sense of how they really feel about personal decisions from whom to marry to what job to take.
— Daniel Goleman, Emotional Intelligence