“Its no secret that a Conscience can sometimes be a Pest, Its no Secret that Ambition bites the Nails of Success”

Original: (it) Il segreto del successo è capire ciò che può colpire.
Source: prevale.net

Lecture III
Lectures on Art (1870)

Source: The Six Rules of Maybe

Source: Green Mars (1993), Chapter 9, “The Spur of the Moment” (p. 480)

Lummox (1923)

As quoted in Murphy's Law Book Two : More Reasons Why Things Go Wrong (1980) by Arthur Bloch, p. 47; similar statements became a routine part of the comedic performances of George Burns.
Attributed

Source: Speech at banquet of the National Union of Conservative and Constitutional Associations, Crystal Palace, London (24 June 1872), cited in "Mr. Disraeli at Sydenham," The Times (25 June 1872), p. 8.

In Herbert F. Vetter, " Not The Average Philosopher http://www.harvardsquarelibrary.org/unitarians/hartshorne.html", Harvard Magazine, May/June 1997, Volume 99, Number 5. On his selection to the Library of Living Philosophers.