High-functioning depression: between inner darkness and outer brilliance:

departure from normal function or feeling which is noticed by a patient, reflecting the presence of an unusual state, or of a disease; subjective, observed by the patient, cannot be measured directly

state of low mood and aversion to activity, which can affect a person's thoughts, behavior, motivation, feelings, and sense of well-being

optical property describing the ability of a surface to reflect light in a specular direction