Discourses, "In What a Man Ought to be Exercised Who Has Made Proficiency; and That We Neglect the Chief Things" (§2)

“The third topic is that which immediately concerns those who are making proficiency, that which concerns the security of the other two, so that not even in sleep any appearance unexamined may surprise us, nor in intoxication, nor in melancholy. This, it may be said, is above our power.”