“Adam, at Eve's grave: Wheresoever she was, THERE was Eden.”
Eve's Diary
Source: The Diary of Adam and Eve
“Adam, at Eve's grave: Wheresoever she was, THERE was Eden.”
Eve's Diary
Source: The Diary of Adam and Eve
“It usually takes me two or three days to prepare an impromptu speech.”
Variant: It usually takes more than three weeks to prepare a good impromptu speech.
Pudd'nhead Wilson's New Calendar, Ch. XLVIII
Following the Equator (1897)
Variant: To get the full value of joy you must have someone to divide it with.
Variant: April 1. This is the day upon which we are reminded of what we are on the other three hundred and sixty-four.
Source: Pudd'nhead Wilson and Other Tales
Following the Equator (1897)
Source: Pudd'nhead Wilson's New Calendar, Ch. XII
Commonly attributed to Twain in computer contexts and post-2000 inspirational books — the first sentence has also been attributed to Agatha Christie and Sally Berger.
Misattributed
Letter to Clara Spaulding (20 August 1886)
“The lack of money is the root of all evil.”
This appears in Twain's posthumous The Refuge of the Derelicts (1905), but it had already been published by other writers.
The earliest citation found in Google Books is a 1872 article by Richard Bowker: "Our Crime Against Crimes" https://books.google.com/books?id=YZgBAAAAYAAJ&pg=PA68&dq=The+lack+of+money+is+the+root+of+all+evil&hl=en&sa=X&ved=0ahUKEwjWi5DE1crLAhUI3mMKHeSdB0YQ6AEIKzAB#v=onepage&q=%22lack%20of%20money%22&f=false, in The Herald of Health, vol. 19 no. 2, New York: Wood & Holbrook, February 1872. The saying is placed within quotation marks, perhaps indicating that it was already well-known.
A precursor is found in an article from 1859 https://books.google.com/books?id=gpdEAQAAMAAJ&pg=PA209&dq=The+lack+of+money+is+the+root+of+all+evil&hl=en&sa=X&ved=0ahUKEwjWi5DE1crLAhUI3mMKHeSdB0YQ6AEINTAD#v=onepage&q=%22lack%20of%20gold%22&f=false: It is very well to repeat, parrot-like, the old axiom that “the love of gold is the root of all evil;” but it is very certain that in truth—the lack of gold is the great incentive to crime.
Disputed