“There can be no dedication to Canada's future without a knowledge of its past.”

Bodhicaryavatara

Speech at Founding Rally of the Organization of Afro-American Unity (28 June 1964), as quoted in By Any Means Necessary (1970)
By any means necessary: speeches, interviews, and a letter (1970)
Context: Armed with the knowledge of our past, we can with confidence charter a course for our future. Culture is an indispensable weapon in the freedom struggle. We must take hold of it and forge the future with the past.

Speech at Founding Rally of the Organization of Afro-American Unity (28 June 1964), as quoted in By Any Means Necessary (1970)
By Any Means Necessary (1970)

This is sometimes attributed to Augustine, but the earliest known occurrence is in Persian Rosary (c. 1929) by Ahmad Sohrab (PDF) http://magshare.net/narchive/NArchive/Misc/Raw_Data/A_Persian_Rosary_by_Mirza_Ahmad_Sohrab.pdf, which probably originates as a paraphrase of a statement in Oscar Wilde's 1893 play A Woman of No Importance: "The only difference between the saint and the sinner is that every saint has a past and every sinner has a future."
Misattributed

1910s, The Progressives, Past and Present (1910)
Context: Inasmuch as it is so often impossible to punish wrongs done in the past, and to prevent the consequences of the wrongs thus committed being felt by one innocent class, without shifting the burden to the shoulders of another innocent class, we ought to provide that hereafter business shall be carried on from its inception in such a way as to prevent swindling. Incidentally, this will also tend to prevent that excessive profit by one man, which may not be swindling, under existing laws, but which nevertheless is against the interest of the commonwealth. To know all the facts is of as much interest to the investor and the wage-worker as to the shipper, the producer, the consumer. Full knowledge of the past helps us in dealing with the future. If we find that high rates are due to overcapitalization n the past, or to any kind of sharp practice in the past, then, whether or not it is possible to take action which will partly remedy the wrong, we are certainly in a better position to prevent a repetition of the wrong.

Kenneth Boulding in the foreword of: Fred Polak (1972) The image of the future http://storyfieldteam.pbworks.com/f/the-image-of-the-future.pdf, p. V
1970s

Selections from the Works of Su-Tung-P'o (1931), as quoted in The Illustrated London News, Vol. 180 (1932), ed. 1, p. 254

Source: The Neverending Story