Progress, far from consisting in change, depends on retentiveness. When change is absolute there remains no being to improve and no direction is set for possible improvement; and when experience is not retained, as among savages, infancy is perpetual. Those who cannot remember the past are condemned to repeat it. In the first stage of life the mind is frivolous and easily distracted; it misses progress by failing in consecutiveness and persistence. This is the condition of children and barbarians, in which instinct has learned nothing from experience.
-George Santayana
Above is the source, really just ‘one of the sources’, for the idea of ‘those that don’t learn from the past are doomed to repeat it’. Like most things, someone already thought/said/wrote this before he did, but that doesn’t diminish George’s version.