Selected quotation
"Life was not a valuable gift, but death was. Life was a fever-dream made up of joys embittered by sorrows, pleasure poisoned by pain, a dream that was a nightmare-confusion of spasmodic and fleeting delights, ecstasies, exultations, happinesses, interspersed with long-drawn miseries, griefs, perils, horrors, disappointments, defeats, humiliations, and despairs - the heaviest curse devisable by divine ingenuity; but death was sweet, death was gentle, death was kind; death healed the bruised spirit and the broken heart, and gave them rest and forgetfulness; death was man's best friend; when man could endure life no longer, death came and set him free."
~ Mark Twain, "Letters From the Earth"
Various books with quotations, aphorisms and proverbs:
America's Popular Sayings: Over 1600 Expressions on Topics from Beauty to Money and Everything In Between
The Ultimate Guide to the Perfect Word: Quotes - Titles - Poetry - Tips - Words
The Oxford Dictionary of Quotations
Positive Thinking Every Day: An Inspiration for Each Day of the Year
365 Inspirational Quotes (365 Days Perpetual Calendars)
Ancient Wisdom: The Book of Proverbs With Devotions for Today
Best Quotations for All Occasions
A Continual Feast: Words of Comfort and Celebration, Collected by Father Tim
Apronisms: Pocket Wisdom for Every Day
Offerings: Buddhist Wisdom for Every Day (Offerings for Humanity)
Doonesbury.com's The War in Quotes
The Book of Positive Quotations, 2nd Edition