“It has been the resolution of mankind in all ages of the world. No people, no age, ever threw away the fruits of past wisdom, or the enjoyment of present blessings, for visionary schemes of ideal perfection. It is the knowledge of the past, the actual infliction of the present, that has produced all changes, all innovations, and all improvements — not (as is pretended) the chimerical anticipation of possible advantages, but the intolerable pressure of long-established, notorious, aggravated, and growing abuses.”

Source: "Some Perplexities about time: with an attempted solution" (1925), p. 149. as cited in: Jonathan Gorman, "The transmission of our understanding of historical time." Historia Social y de la Educación 1.2 (2012): 129-152.

Quote in "Picasso", Hans L. C. Jaffe, Thames and Hudson Ltd
Attributed from posthumous publications

As quoted in "Humanity will survive information deluge — Sir Arthur C Clarke" in OneWorld South Asia (5 December 2003) http://southasia.oneworld.net/article/view/74591/1
2000s and attributed from posthumous publications

Characters, Ch. 2 : A Christmas Dinner
Sketches by Boz (1836-1837)
Context: Christmas time! That man must be a misanthrope indeed, in whose breast something like a jovial feeling is not roused — in whose mind some pleasant associations are not awakened — by the recurrence of Christmas. There are people who will tell you that Christmas is not to them what it used to be; that each succeeding Christmas has found some cherished hope, or happy prospect, of the year before, dimmed or passed away; that the present only serves to remind them of reduced circumstances and straitened incomes — of the feasts they once bestowed on hollow friends, and of the cold looks that meet them now, in adversity and misfortune. Never heed such dismal reminiscences. There are few men who have lived long enough in the world, who cannot call up such thoughts any day in the year. Then do not select the merriest of the three hundred and sixty-five for your doleful recollections, but draw your chair nearer the blazing fire — fill the glass and send round the song — and if your room be smaller than it was a dozen years ago, or if your glass be filled with reeking punch, instead of sparkling wine, put a good face on the matter, and empty it off-hand, and fill another, and troll off the old ditty you used to sing, and thank God it’s no worse. Look on the merry faces of your children (if you have any) as they sit round the fire. One little seat may be empty; one slight form that gladdened the father’s heart, and roused the mother’s pride to look upon, may not be there. Dwell not upon the past; think not that one short year ago, the fair child now resolving into dust, sat before you, with the bloom of health upon its cheek, and the gaiety of infancy in its joyous eye. Reflect upon your present blessings — of which every man has many — not on your past misfortunes, of which all men have some. Fill your glass again, with a merry face and contented heart. Our life on it, but your Christmas shall be merry, and your new year a happy one!

Source: Das Ressentiment im Aufbau der Moralen (1912), L. Coser, trans. (1973), p. 68

Siddhartha (1922)
Context: Listen my friend! I am a sinner and you are a sinner, but someday the sinner will be Brahma again, will someday attain Nirvana, will someday become a Buddha. Now this "someday" is illusion; it is only a comparison. The sinner is not on his way to a Buddha-like state; he is not evolving, although our thinking cannot conceive things otherwise. No, the potential Buddha already exists in the sinner; his future is already there. The potential hidden Buddha must be recognized in him, in you, in everybody. The world, Govinda, is not imperfect or slowly evolving along a path to perfection. No, it is perfect at every moment; every sin already carries grace within it, all small children are potential old men, all sucklings have death within them, all dying people — eternal life. It is not possible for one person to see how far another is on the way; the Buddha exits in robber and the dice player; the robber exists in the Brahmin. During deep meditation it is possible to dispel time, to see simultaneously all the past, present, and future, and then everything is good, everything is perfect, everything is Brahman.

Rabbit is Rich (1981)

What Is Religion? (1899) is Ingersoll's last public address, delivered before the American Free Religious association, Boston, June 2, 1899. Source: The Works of Robert G. Ingersoll, Dresden Memorial Edition Volume IV, pages 477-508, edited by Cliff Walker. http://www.positiveatheism.org/hist/ingwhatrel.htm
Variant: The present is the child, and the necessary child, of all the past, and the mother of all the future.