This saying appears in many different forms, but the earliest version
is probably that of the poet and philosopher George Santayana: "Those
who cannot remember the past are condemned to repeat it."
"Notable Quotations from George Santayana
'Those who cannot remember the past are condemned to repeat it.'
Life of Reason, Reason in Common Sense, Scribner's, 1905, page 284"
Collecting and Editing the Works of George Santayana
"The New Dictionary of Cultural Literacy, Third Edition. 2002.
Those who cannot remember the past are condemned to repeat it.
Studying history is necessary to avoid repeating past mistakes. This
saying comes from the writings of George Santayana, a Spanish-born
American author of the late nineteenth and early twentieth centuries."
Bartleby: The New Dictionary of Cultural Literacy
"The Columbia World of Quotations. 1996.
QUOTATION: Those who cannot remember the past are condemned to repeat it.
ATTRIBUTION: George Santayana (1863?1952), U.S. philosopher, poet.
Life of Reason, 'Reason in Common Sense,' ch. 12 (1905-6).
William L. Shirer made these words the epigraph for his Rise and Fall
of the Third Reich (1959)."
Bartleby: The Columbia World of Quotations
Here's an interesting little article about the many versions of this famous quote:
Jaywalker Magazine: Forget the Past!
My Google search strategy:
Google Web Search: santayana "common sense" "to repeat it"
I hope this is precisely what you need to know. Please let me know if
anything requires clarification.