“Science is a wonderful thing if one does not have to earn one's living at it.”
Letter to California student E. Holzapfel (March 1951) Einstein Archive 59-1013, p. 57
Attributed in posthumous publications, Albert Einstein: The Human Side (1979)
Foreword of "Man and his Gods" by Homer W. Smith
Attributed in posthumous publications, Einstein and Religion (1999)
Letter to Michele Besso (10 September 1952), Letter n°190, Correspondance, 1903-1955 (1972), by Pierre Speziali and Michele Angelo Besso
1950s
1920s, Viereck interview (1929)
Contribution in Albert Einstein: Philosopher-Scientist, p. A. Schilpp, ed. (The Library of Living Philosophers, Evanston, IL (1949), p. 684). Quoted in Einstein's Philosophy of Science http://plato.stanford.edu/entries/einstein-philscience/
1940s
“One may say "the eternal mystery of the world is its comprehensibility."”
From the article "Physics and Reality" (March 1936), reprinted in Out of My Later Years (1956). The quotation marks may just indicate that he wants to present this as a new aphorism, but it could possibly indicate that he is paraphrasing or quoting someone else — perhaps Immanuel Kant, since in the next sentence he says "It is one of the great realizations of Immanuel Kant that the setting up of a real external world would be senseless without this comprehensibility."
Other variants:
The eternally incomprehensible thing about the world is its comprehensibility.
In the endnotes to Einstein: His Life and Universe by Walter Isaacson, note 46 on p. 628 http://books.google.com/books?id=cdxWNE7NY6QC&lpg=PP1&pg=PA628#v=onepage&q&f=false says that "Gerald Holton says that this is more properly translated" as the variant above, citing Holton's essay "What Precisely is Thinking?" on p. 161 of Einstein: A Centenary Volume edited by Anthony Philip French.
The most incomprehensible thing about the world is that it is comprehensible.
This version was given in Einstein: A Biography (1954) by Antonina Vallentin, p. 24, and widely quoted afterwards. Vallentin cites "Physics and Reality" in Journal of the Franklin Institute (March 1936), and is possibly giving a variant translation as with Holton.
The most incomprehensible thing about the world is that it is at all comprehensible.
As quoted in Speaking of Science (2000) by Michael Fripp
The eternal mystery of the world is its comprehensibility … The fact that it is comprehensible is a miracle.
As quoted in Einstein: His Life and Universe by Walter Isaacson, p. 462 http://books.google.com/books?id=cdxWNE7NY6QC&lpg=PP1&pg=PA462#v=onepage&q&f=false. In the original essay "The fact that it is comprehensible is a miracle" appears at the end of the paragraph that follows the paragraph in which "The eternal mystery of the world is its comprehensibility" appears.
1930s
“Education is that which remains, if one has forgotten everything he learned in school.”
Einstein did write this quote in "On Education" from 1936, which appeared in Out of My Later Years, but it was not his own original quip, he attributed it to an unnamed "wit".
Very popular in French: "La culture est ce qui reste lorsque l’on a tout oublié" (Culture is that which remains, if one has forgotten everything). Attributed in French to Édouard Herriot (1872-1957) and, in English, sometimes to Ortega y Gasset. Another French variant is "la culture est ce qui reste lorsqu'on a oublié toutes les choses apprises" (Culture is that which remains if one has forgotten everything one has learned), which appears in the 1912 book Propos Critiques by Georges Duhamel, p. 14 http://books.google.com/books?id=Xpk_AAAAIAAJ&q=%22la+culture+est+ce+qui+reste+lorsqu%27on+a+oubli%C3%A9+toutes+les+choses+apprises%22#search_anchor. And another English variant is "Culture is that which remains with a man when he has forgotten all he has learned" which appears in The Living Age: Volume 335 from 1929, p. 159 http://books.google.com/books?id=tHFRAAAAYAAJ&q=%22Culture+is+that+which+remains+with+a+man+when+he+has+forgotten+all+he+has+learned%22#search_anchor, where it is attributed to "Edouard Herriot, French Minister of Education". Another English variant is "Education is that which remains behind when all we have learned at school is forgotten", which appears in The Education Outlook, vol. 60 p. 532 http://books.google.com/books?id=dNcgAQAAMAAJ&pg=RA1-PA532#v=onepage&q=%22education%20is%20that%20which%20remains%22&f=false (from an issue dated 2 December 1907), where it is attributed to Ralph Waldo Emerson.
The saying is found in an 1891 article by Swedish writer Ellen Key https://en.wikipedia.org/wiki/Ellen_Key, "Själamorden i skolorna", which was published in the journal "Verdandi", no. 2, pages 86-98 (the saying is on p. 97). The same article was republished later as a chapter in her 1900 book "Barnets Århundrade". Here is the quote in Swedish ( p. 160 https://archive.org/stream/barnetsrhundrade02ellenkey#page/n167/mode/2up): Men bildning är lyckligtvis icke blott kunskap om fakta, utan enligt en ypperlig paradox: »det, som är kvar, sedan vi glömt allt, vad vi lärt». Here it is from the 1909 English translation of the book ( p. 231 https://archive.org/stream/centurychild00frangoog#page/n246/mode/2up): "But education happily is not simply the knowledge of facts, it is, as an admirable paradox has put it, what is left over after we have forgotten all we have learnt." From the way Ellen Key puts it, she doesn’t take credit for the saying, but rather refers to it as an already known “paradox” that she explicitly puts between quotation marks.
Misattributed
“A happy man is too satisfied with the present to dwell too much on the future.”
Un homme heureux est trop content du présent pour trop se soucier de l'avenir.
From "Mes Projets d'Avenir", a French essay written at age 17 for a school exam (18 September 1896). The Collected Papers of Albert Einstein Vol. 1 (1987) Doc. 22.
1890s
Variante: A happy man is too satisfied with the present to dwell too much on the future.
“To take those fools in clerical garb seriously is to show them too much honor.”
Comment on the Union of Orthodox Rabbis after expelling a rabbi because of his disbelief in God as a personal entity.
Attributed in posthumous publications, Einstein's God (1997)
“Sometimes one pays most for the things one gets for nothing.”
Quoted in The Ultimate Quotable Einstein by Alice Calaprice (2010), p. 230
1920s, Viereck interview (1929)
“It is a scale of proportions which makes the bad difficult and the good easy.”
Er ist eine Skala der Proportionen, die das Schlechte schwierig und das Gute leicht macht.
On the Modulor. Letter sent to Le Corbusier (1946); quoted in Modulor (1953)
1940s
Fonte: Attributed in posthumous publications, Einstein and the Poet (1983), p. 103
Letter to Guy H. Raner Jr. (2 July 1945), responding to a rumor that a Jesuit priest had caused Einstein to convert to Christianity, quoted in an article by Michael R. Gilmore in Skeptic magazine, Vol. 5, No. 2 (1997)
1940s
“Compound interest is the most powerful force in the universe.”
Variants: "... is man’s greatest invention" and "... is the eighth wonder of the world".
May add: "He who understands it, earns it; he who doesn’t, pays it."
This Snopes article http://www.snopes.com/quotes/einstein/interest.asp concluded that its status was uncertain, while this post from The Quote Investigator http://quoteinvestigator.com/2011/10/31/compound-interest/ concludes it is most likely a false attribution, since variants of the quote date back to at least 1916, with the early variants not being attributed to Einstein.
Disputed
From his "Autobiographische Skizze" (18 April 1955), original German version here http://philoscience.unibe.ch/documents/kursarchiv/WS99/Skizze.pdf. Translation from Einstein from 'B' to 'Z by John J. Stachel (2001), p. 5 http://books.google.com/books?id=OAsQ_hFjhrAC&lpg=PP1&pg=PA5#v=onepage&q&f=false.
Original German version: Formulierung technischer Patente ein wahrer Segen für mich. Sie zwang zu vielseitigem Denken, bot auch wichtige Anregungen für das physikalische Denken. Endlich ist ein praktischer Beruf für Menschen meiner Art überhaupt ein Segen. Denn die akademische Laufbahn versetzt einen jungen Menschen in eine Art Zwangslage, wissenschaftliche Schriften in impressiver Menge zu produzieren — eine Verführung zur Oberflächlichkeit, der nur starke Charaktere zu widerstehen vermögen. ("Autobiographische Skizze", p. 12)
1950s
Variante: "Working on the final formulation of technological patents was a veritable blessing for me. It enforced many-sided thinking and also provided important stimuli to physical thought. [Academia] places a young person under a kind of compulsion to produce impressive quantities of scientific publications — a temptation to superficiality." As quoted in "Who Knew?" http://www7.nationalgeographic.com/ngm/0505/resources_who.html at NationalGeographic.com (May 2005).
“Time and space are modes by which we think and not conditions in which we live.”
Earliest source located that attributes this to Einstein is the 1975 book The Nature of Scientific Discovery: A Symposium Commemorating the 500th Anniversary of the Birth of Nicolaus Copernicus edited by Owen Gingerich, p. 585 http://books.google.com/books?id=Ub3gAAAAMAAJ&q=%22certainly+a+central%22#search_anchor. But long before that, the 1944 book Einstein: An Intimate Study of a Great Man by Dimitri Marianoff and Palma Wayne contains the following quote on p. 62: "But Einstein came along and took space and time out of the realm of stationary things and put them in the realm of relativity—giving the onlooker dominion over time and space, because time and space are modes by which we think and not conditions in which we live." It appears from the quote that the authors were giving their own description of Einstein's ideas, not quoting him.
Misattributed
(28 September 1932), p. 106
Attributed in posthumous publications, Albert Einstein: The Human Side (1979)
Conversations with Einstein by Alexander Moszkowski (1971), p. 69 http://books.google.com/books?id=_D3wAAAAIAAJ&q=%22first+lessons+should+contain+nothing+but+what%22#search_anchor. This is just Moszkowski's English translation of a statement he attributed to Einstein in his 1922 book Einstein, Einblicke in seine Gedankenwelt, p. 77 http://books.google.com/books?id=6zHPAAAAMAAJ&pg=PA77#v=onepage&q&f=false: "Was die Physik betrifft, fuhr Einstein fort, so darf für den ersten Unterricht gar nichts in Frage kommen, als das Experimentelle, anschaulich-Interessante. Ein hübsches Experiment ist schon an sich oft wertvoller, als zwanzig in der Gedankenretorte entwickelte Formeln." As Moszkowski makes clear in the original German text, this "quotation" is a paraphrasing of his conversation with Einstein.
Attributed in posthumous publications
"Self-Portrait" (1936), p. 5 http://books.google.com/books?id=Q1UxYzuI2oQC&lpg=PP1&pg=PA5#v=onepage&q&f=false
1950s, Out of My Later Years (1950)