Who has not at one time or other felt a sourness, wrath, selfishness, envy and pride, which he could not tell what to do with, or how to bear, rising up in him without his consent, casting a blackness over all his thoughts, and then as suddenly going off again, either by the cheerfulness of the sun or air, or some agreeable accident, and again, at times, as suddenly returning upon him? Sufficient indications are these to every man that there is a dark guest within him… often lulled to sleep by worldly light and amusements.

William Law (1686 – 1761)