Meditations, Book II, Section 6

Meditations, Book II, Section 6:

These things thou must always have in mind: What is the nature of the universe, and what is mine—in particular: This unto that what relation it hath: what kind of part, of what kind of universe it is: And that there is nobody that can hinder thee, but that thou mayest always both do and speak those things which are agreeable to that nature, whereof thou art a part.