Hope & Resilience
* "Even the darkest nights will end and the sun will rise."
* "The greatest glory in living lies not in never falling, but in rising every time we fall." - Nelson Mandela
* "Hope is a good breakfast, but it is a bad supper." - Francis Bacon
Mystery & Intrigue
* "The truth is out there." - The X-Files
* "There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy." - Hamlet by William Shakespeare
* "The past is never dead. It's not even past." - William Faulkner
Love & Relationships
* "Love is a battlefield." - Pat Benatar
* "All you need is love." - The Beatles
* "The best and most beautiful things in the world cannot be seen or even touched - they must be felt with the heart." - Helen Keller
Adventure & Exploration
* "The world is a book, and those who do not travel read only one page." - Saint Augustine
* "To travel is to discover that everyone is wrong about other countries." - Aldous Huxley
* "Adventure is worthwhile." - Amelia Earhart
Self-Discovery & Growth
* "The journey of a thousand miles begins with a single step." - Lao Tzu
* "Be the change that you wish to see in the world." - Mahatma Gandhi
* "The only way to do great work is to love what you do." - Steve Jobs
Humor & Irony
* "Life is a comedy for those who think, a tragedy for those who feel." - Horace Walpole
* "I'm not sure what's wrong with me, but I'm sure it's contagious." - Unknown
* "There are two ways to be happy: improve your reality or lower your expectations." - Unknown
Ultimately, the best motto for your book depends on its genre, tone, and message. Choose something that resonates with you and that will draw readers in.