Foundational Text for Positive Mental Attitude:
The King James Bible
The Woman's Bible by Elizabeth Cady Stanton [1895]

Other Online Books:
As A Man Thinketh by James Allen
Acres of Diamonds by Dr. Russell H. Conwell.
The Magic Story by Frederic Van Rensselaer Dey
The Greatest Thing in the World by Henry Drummond
A Message to Garcia by Elbert Hubbard
The Majesty of Calmness by William George Jordan
Character Building Thought Power by Ralph Waldo Trine.
The Science of Getting Rich by Wallace D Wattles [1910]
Think and Grow Rich by Napoleon Hill [1938]
The Science of Mind by Ernest Holmes [1926]

The Fables of Aesop tr. by George Fyler Townsend, [1887]
The Transcendentalist by Ralph Waldo Emerson
The Creative Process in the Individual by Thomas Troward
The Law and the Word by Thomas Troward
Your Invisible Power by Genevieve Behrend
Your Word is Your Wand by Florence Shovel Shinn