Definitions: (1) the art of thinking and reasoning justly; (2) formally true or valid; (3) using correct rationality; (4) a persuasive argument with an expected and necessary progression; one thing rationally and sensibly following each statement; (5) the presentation of facts, feelings, and/or beliefs so as to give the listener reason to accept a given conclusion

Saying: As above, so below.

• Remember there’s no such thing as a small act of kindness. Every act creates a ripple with no logical end. — Scott Raymond Adams (1957-) American cartoonist
• We are approaching a new age of synthesis. Knowledge cannot be merely a degree or a skill… it demands a broader vision, capabilities in critical thinking and logical deduction without which we cannot have constructive progress. — Sir Ka-shing Li (1928-) Hong Kong philanthropist