“We learn from a passage in Strabo, that it was a dogma of the Gaulish Druids that the universe was immortal, but destined to survive catastrophes both of fire and water. That this doctrine was communicated to them from the East, with much of their learning, cannot be doubted.”

This opinion is consistent with sound reason: if we consider the light that is without body, we shall perceive that of such light the source cannot be a body, but rather the simple action of a mind, which spreads itself by means of illumination as far as its proper seat; to which the middle region of the heavens is contiguous, from which place it shines forth with all its vigour and fills the heavenly orbs, illuminating at the same time the whole universe with its divine and pure radiance.
Upon the Sovereign Sun (362)

Source: 2000s, A little book of f-laws: 13 common sins of management, 2006, p. 37 cited in: Andrew Carey (2008) Inside Project Red Stripe: Incubating Innovation and Teamwork at the Economist. p. 49.

Source: De architectura (The Ten Books On Architecture) (~ 15BC), Book I, Chapter IV, Sec. 10

Nelson Mandela on character, Foreign Correspondent's Association's Annual Dinner, Johannesburg, South Africa (21 November 1997). Source: From Nelson Mandela By Himself: The Authorised Book of Quotations © 2010 by Nelson R. Mandela and The Nelson Mandela Foundation http://www.nelsonmandela.org/content/mini-site/selected-quotes
1990s

Source: Facing the Lion, Being the Lion: Finding Inner Courage Where It Lives

Source: Inkspell

Often attributed to Desmond Tutu, actual source is G. W. F Hegel: What experience and history teach is this — that nations and governments have never learned anything from history, or acted upon any lessons they might have drawn from it. Lectures on the Philosophy of History (1832)
Misattributed