Final answer:
The quotes by John Adams and Richard Nixon relate to the concept of the Rule of Law.
Step-by-step explanation:
The presidential quotes provided relate to the concept of the Rule of Law. John Adams' quote, 'I want a government of laws, not men,' emphasizes the importance of a legal system that applies to everyone equally and is not subject to personal discretion or arbitrary decision-making. This aligns with the principle of the rule of law, where no individual or institution is above the law.
On the other hand, Richard Nixon's quote, 'When the president does it, it is not illegal,' suggests a belief in executive privilege and that the president is exempt from the law. This contradicts the principle of the rule of law, as it implies that the president is above the law.